Man's encounter with “hallucinogenic” mushrooms originated in the Stone Age and gave rise to shamanic and religious cults, some that have been preserved to this day. For over twenty years the author has been carrying out investigations in the scientific field of psychoactive fungi entomycology and in this volume he has collected the results of the main research, which took him to the desert of Sahara, among the Dravidian tribes of India, on the Aztec and Messian Mayan pyramids, in the African equatorial forest and in front of capitals and frescoes of several European Romanesque churches, in search of knowledge , cults and uses of “sacred mushrooms” among current and past populations. The studies presented here explore the new frontiers of ethnomychology, following the discoveries of R.G. WASSON over the years 1960-70. One of the most significant data is the recognition of an underlying, religious and mythological relationship that the pre-Christian and Christian people have intertwined with psychoactive mushrooms.