Happy Spring. Time to do some planting...
Once again, back to the maps. Today's inspiration - What are those trees doing underground? A bit of a mystery, that. So like some prior exercises, here is a space where the "treasure" isn't loot to carry off, but a resource, and potentially some intelligence as to its use. Of course, because this nursery is underground, that implies that the trees themselves have value, and perhaps are something that groups or individuals may wish to keep undisclosed.
And, of course, the caretaker of the place has had a mishap. Fortunately, they were prescient enough to leave some "help" behind to keep an eye on the place, and keep the trees watered. An incautious party that slays as it goes may lose a secondary resource in the residents. And because places under the earth often have a history of multiple tenants, there are a few artifacts from different groups may be found.
Alternatively, a bunch of halflings would probably just move in and set up a grow-op.