Upon reflection, I realized that I wasn't entirely clear about what I was doing with my post yesterday. Those were obviously not entire adventures. They were meant to be set-ups for adventure opportunities that could be fleshed out later on. It was the result of some twenty-to-thirty minutes of rumination. For me, that's useful enough to keep in my back pocket as something that can be used to make tavern rumors or to otherwise throw out teasers at the players (in game or between sessions) to see what they latch onto, based on which actual adventures can then be built.
Well, aside from the first one, which would be an emergent-complication-maker.
In the interest of completeness, though, I suppose I should've added extra notes of how I'd approach using each of them, so here we go:
1. Instant Idea, Just Add Magic (Item)
As I'd said, put that drawback on a sensible magic item, and keep it in mind at all times. Mounts and mules can become unruly and prone to flight, skittish animals (like mice or birds) can make a spectacle of fleeing the bearer's presence, aggressive animals can focus on them in combat, beastly humanoid-hybrids (beastmen, lizardmen, deep ones, lycanthropes, jackalweres, centaurs, sphinxes, or anything else in touch with an animalistic aspect) can be predisposed towards hostile reactions, and so forth. The character would likely be a menace to many rural environments, particularly agrarians, though they could also have value as a natural pest-repellent (which other people may want to make a permanent fixture of their settlement, depending on the circumstances; more conflicts ahoy!). The character could make it harder to move through natural environments stealthily and/or might increase the chances for random encounters with animals. How minor or difficult you want to make the effects can be tuned to what would be the most enjoyable for the group, and it should be weighed against the benefits of the magic item because the ideal reaction is when the players are left debating whether the boons are worth the problems. For further inspiration, consider this video from Seth Skorkowsky of the vorpal blade that his players came to loathe.
2. Antipathetic Druid
This one should be a pretty straightforward set-up: either the druid was a fixture around the players' own hometown who incites curiosity with a sudden change in demeanor or the druid was a known element of a nearby village from which rumors of villager consternation and speculated causes reach the players. If they choose to investigate, come up with an actual explanation for what happened, and play it out from there. What actually happened with the druid? Are they open to talking about it, are they reticent and resentful of unwanted curiosity, or are they drinking themselves into such a constant stupor as to render the former questions moot? Maybe the players figure out and resolve the problem, maybe the players kill the druid and argue about whether or not to adopt the role for themselves, or maybe they come up with something else entirely.
3. Lonely Wizard
This one should be even more straightforward: there's a cocaine wizard in an isolated tower who's been making crazy monsters; are you bad enough adventurers to do something about it? Play it like Howard's Tower of the Elephant, like Die Hard-in-a-forest, like Ghost Tower of Inverness, or whatever else you want. What horrible monstrosities are out there? Are they organized or at each others' throats? What treasures can be found in the tower or in the woods? Is the wizard even still alive? Does spending time in the tower actually cause insanity? That's all your time to shine.
Think of this as a slow-burning mystery. The players do their normal stuff, but they keep seeing incidents of animal unrest (or their aftermath) in what should be safe places. In the narrative, this should start out slow and build up over time, though whether to actually play it out like that or to just summarize that and throw the players in as things have gotten to a problematic level is up to how long you want to run it (for the former approach, might I recommend using Beyond The Wall: Further Afield's idea of threat packs to model background plots that grow over time?). Include some incident(s) that target the player characters directly to give them more personal motivation, if necessary. If you want to play up the weirdness, keep the cult of cosmic listeners very subtle and possibly even unaware of what they're doing; even if the players manage to solve the apparent situation, there's no telling when something like it might happen again, and there's no indication of who else might be able to hear the desires of the universe. If you want more action, make the cult more obvious and make it possible to actually root it out and deal with it permanently. In either case, of course, don't presuppose that the players will want to stop the cult! Given the current state of the real world, environmentalist themes can come off quite sympathetically, and regardless of that, some of the best results of adventures involving cults come about when the players either join, take over, or find a way to manipulate the cult's actions to their own ends. Even if you're running a more lighthearted game where nobody asks why the unabashedly evil and crazy Cult of the Planet-Fucker has no shortage of members, those moments where the cult leaders tell the adventurers We Can Rule Together work better when the players know you aren't going to shut them down if they agree to it.
5. False Flag
Whenever you want a sequence of events to happen, your only safe bet is if the players weren't involved while it was happening, lest they actually exercise some agency by getting involved. The way I'd handle this is to pick a town near to where the players are which they haven't visited in a while (if ever) and spread some rumors about it having had problems with a vampire (if your players are heroic-types) and/or about it having incredible decreases in crops lost to pests with suggestions of magical trickery (if your players are more self-interested). When they get there, the woman's animal antipathy has spread to the point of there being no animals left in the town; if the players have animals with them, they should show a sudden aversion to following along (if any of the players are a bit beastly themselves, play up feelings of discomfort, confusion, and/or anger; maybe give a small penalty to any dice rolls to do stuff that wouldn't be acting against the woman directly, but just tell the number impacts and let them figure out the trend for themselves, if reasonable). Things look idyllic on the surface, but there's a strong undercurrent of forced positivity, in a very Stepford Smiler way. Naturally, the woman will cross paths with the players for some reason and nominate one or more of them as suitable suitors to attend her keep, and how things go from there is up to you. Is she actually a vampire, or had it just been a ruse to set herself up as a savior, or was there an actual vampire at the keep that she trapped/killed? In the latter case, was it (or its remains) what was responsible for the antipathy? Is she playing out some twisted revenge on the town for her rough childhood, or is she just trying to do her best to fit in? Are her suitors at the keep dead, or are they enjoying themselves too much to want to leave, and in the latter case, is it by magic or genuine? Do the townspeople actually want to be rid of her, or do they think that the missing people and animal antipathy is a fair price for their comfort and security? Is there actually nobody in town who remembers the beggar girl, or was that just an exaggeration to obfuscate the elder who suspects the real truth? I think it's pretty blatant that I took inspiration from C.A. Smith's The Dark Eidolon, but there's no reason why you can't take things in another direction.
Of course, there's also no reason why the adventure can't involve the players being around during the vampire attacks. Just don't force the rest of it to go according to the idea seed in that case.
Honestly, this one is probably my favorite of the lot, because it lends itself so well to something that I love: throwing in a hook for another adventure as part of a treasure haul in the middle of a current adventure and letting the players decide which one they want to pursue. In this case, my gut instinct would be to take that write-up more or less directly, just modifying the last entry to have the chronicler flee instead of asking their journal for help, and have it written on a piece of paper found among the belongings of a dead traveler. I might even rip it up into two scraps of paper (one with the dead traveler and one with the nesting materials of whatever killed the traveler, for instance), though that's taking more of a chance for it to go under the radar. Have something on the paper indicate a village nearby that's been abandoned for some time. If the players decide to go there, the man resumes his daily visits, asking them for what they have to offer and inciting animals to attack them if it's not sufficient but paying very well (maybe double or more the true value) for anything that meets his standards. What determines if something meets his standards? What manner of being is he exactly? Does his curse incite only a single attack, or does it stick to the character for some time (maybe even indefinitely)? Is there any cost for simply leaving the town after encountering the man? That's up to you.
As with the previous one, the man could show up in whatever place the players are using as a home base, too. In this case, of course, the mentioned timeline should be thrown out, but he'll keep going around and buying up all the best stuff that he can find (definitely make him purchase things that the players wanted but couldn't afford). He'll start to exhaust what merchants can offer, and that's when the players should see him buying people. If the players get themselves involved with him, the questions in the above paragraph should help you figure out what happens from there.