Galerina marginata
The superficial resemblance between certain deadly poisonous mushrooms and ones that are edible can be chilling.
In cold weather, the deadly poisonous Galerina marginata (formerly known as Galerina autumnalis) can be found in moist Illinois woodlands, popping out of rotted logs everywhere.
At the same time, an edible species known as Flammulina velutipes appears in moist woodlands, sometimes growing side by side with the Deadly Galerina--both chillingly similar at a glance.