Earl Lee (1998, pp. 99-102) brought to my attention the little known fact that Sig-
mund Freud privately took a keen interest in mushrooms. He was knowledgeable about all manner of wild mushrooms, including psychoactive varieties. His son Martin Freud (1957) stated that “the expeditions of young children led by our father, Sigmund Freud, always had a particular purpose

Dan Merkur. Freud’s Mushroom Hunting
http://www.danmerkur.com/pages/online.html