brain mushroom vs false morel

brain mushroom

noun
  • A fungus common in Europe and North America and one of several species of fungi known as false morels, especially Gyromitra esculenta. 

false morel

noun
  • Any of several Ascomycota mushrooms in the genus Gyromitra which bear a resemblance to the highly regarded true morels of the genus Morchella. 

How often have the words brain mushroom and false morel occurred in a corpus of books? (source: Google Ngram Viewer )