The word toadstool appeared first in 14th century England as a reference for a "stool" for toads, possibly inferring an inedible poisonous fungus.

How did toadstools get their name?

Some mushrooms are called toadstools. This nickname probably came from the fact that they looked just like a perfect spot for a toad to sit! Some people believe that the term “toadstool" means a mushroom that is poisonous. This belief may have come from the fact that many toads were considered highly poisonous.

Is it a mushroom or toadstool?

From a scientific perspective, there's no difference between a toadstool and a mushroom. ... In common speech, people tend to use the word toadstool to refer to fungi that are toxic, poisonous, or simply inedible. While the word mushroom is used to describe tasty and edible mushrooms.