D&D adventure concept: it turns out that the Fairy Queen doesn’t actually do anything with the sparkles-in-your-eyes and memories-of-a-summer’s-day and other sundry intangibles and abstractions she’s been scamming mortals out of for the last few centuries.
Whatever she had planned for them didn’t pan out, but she never ordered her minions to stop collecting them; by the time it became clear that the project was a no-go, expectations had already been set, and when you’re the Queen of the Fairies you can’t very well admit to having a bad idea.
She’s just been discretely dumping them down a disused well for hundreds of years, and the resulting effluvium of spoiled virtue and rotten whimsy has begun to contaminate the drinking water of a human village downstream – which is where the player characters come in.
It probably doesn’t help that half the Fae economy is now built around buying the stuff- every goblin market accepts your happiest childhood moment as legal tender for their dubious merchandise, and since the queen’s made it fashionable, there are fairy nobles who specialize in certain ephemera.
(Everyone’s a little worried about the Baron of Autumn, who specializes in bespoke Orphan’s Tears.)
But no one’s gonna admit that they don’t know what all this collecting is for, they just know that it’s valuable to the Queen.
Oh, god, imagine if the faerie realm catches on that the Queen no longer has any use for such things? Imagine the faerie realm undergoing an economic collapse!
I’m not gonna say “player characters start out investigating tainted well, end up being responsible for Fairy Realm’s equivalent of collapse of the gold standard” is specifically where I was going with this, but it’s definitely amongst the several possible outcomes I had in mind.