Psilocybe tampanensis is a very rare psychedelic mushroom in the family Hymenogastraceae. Originally collected in the wild in a sandy meadow near Tampa, Florida, in 1977, the fungus would not be found in Florida again until 44 years later. The original Florida specimen was cloned, and descendants remain in wide circulation. The fruit bodies (mushrooms) produced by the fungus are yellowish-brown in color with convex to conic caps up to 2.4 cm (0.9 in) in diameter atop a thin stem up to 6 cm (2.4 in) long. Psilocybe tampanensis forms psychoactive truffle-like sclerotia that are known and sold under the nickname "philosopher's stones". The fruit bodies and sclerotia are consumed by some for recreational or entheogenic purposes. In nature, sclerotia are produced by the fungus as a rare form of protection from wildfires and other natural disasters.

Psilocybe is a genus of gilled mushrooms, growing worldwide, in the family Hymenogastraceae. Many species contain the psychedelic compounds psilocybin and psilocin.