“ 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.”
“ Head priests of a order are buried sitting up with their skeletal hand sticking out of the ground so worshippers can still kiss his hand for a blessing.”
“ Plant that is likely to produce allergic reactions in almost everybody, even by touch. Usage: medicinal, in very exotic foods, non-lethal traps, disabling opponents (have you ever cut an onion,anyway?), spell components, etc.”