McKennaii Psilocybin Cubensis mushrooms are fungi that contain the psychoactive compound psilocybin, a naturally occurring psychedelic compound capable of producing powerful hallucinations and mystical-type experiences, along with other effects. Psilocybin is more commonly known as “magic mushrooms” or “shrooms.” More than 180 species of mushrooms contain psilocybin or its derivative psilocin, and the fungi have a long history of use in Mesoamerican spiritual and religious rituals. They’re also one of the most popular and commonly used psychedelics in the U.S. and Europe.