“ 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.”
“ The babies of a small village has been disappearing lately, rumour has it that a demon living in the forest has taken them. The monster has the appearance of a shriveled old woman. A hag, disheveled, with maniacal appearance, wild-looking hair, and an oversized gaping mouth. Long pendelous breasts. The villagers say she eats the newborns and has sharp claws that are created for mangling. No one dears to challenge her, enter the PCs.”
“ On a location with numerous webs, and at least one big spider, there is a something inside a cocoon. It is humanoid in shape, still moving. If the heroes free it (not before they kill or drive away the spiders), they meet a ... zombie!
The poor zombie wandered the dungeon alone, and tried to kill a big living creature (= a spider). The spider used the usual treatment, even if this victim did not look tasty. The zombie can be easily killed as any other zombie. It got but several doses of spider-poison, so can be something worth if it is extracted. You can mention to a druid or ranger the fact the spider had no poison anymore.”