The party comes across a magic amulet. This amulet will give each user two wishes, but the wishes almost seem to have a mind of their own.
Missions for any campaign in any city of any realm. As long as crime exists, you will be able to use this submission.
Giant mushrooms the size of trees. The stems and parts of the caps can be used in construction, and only the gills are soft enough to eat. An entire fungi-forest can grow in a matter of days, provided the correct conditions. Most fungus trees last about a month before collapsing, but not before a new generation sprouts to provide shade for the next spores.