Psilocybin and psilocin are highly potent natural tryptamine psychedelics and close relatives of DMT, 5-MeO-DMT, and other molecules. These active substances can be found worldwide in various species of mushrooms and have accompanied humanity for a long time in its quest for meaning and spirituality. Through the work of the Mexican curandera Maria Sabina and the founder of ethnomycology, R. Gordon Wasson, psilocybin-containing mushrooms became known as psychedelic catalysts. They are increasingly gaining importance in both psychonautical and medical applications today. This book portrays the psilocybin mushrooms newly discovered and described by German mycologist Jochen Gartz and colleagues since 1983 in monographs, detailing their history, occurrence, potential applications, chemical composition, and more.