The ritual use of magic mushrooms containing psilocybin for mystical or spiritual purposes dates back to pre-Columbian Mesoamerican societies and continues to this day. Trusted Source
Psychoactive mushrooms have been used for thousands of years and have a long history of both medicinal and ceremonial use among indigenous peoples in many parts of the world, including Europe and the Americas.
The American continent is very rich in psychoactive plants and fungi, and many pre-Columbian Mesoamerican cultures used them for magical, therapeutic and religious purposes.
Early uses of psychotogens in Mesoamerica included mushrooms in herb eluxirs.
In european fokelore, a long standing theory is that magic mushrooms were used in the druids religious ceremonies.
There were ceromonial rituals which included mushroom consumption. It was eaten for its hallucinogenic properties because the hallucinations conferred great knowledge and enlightenment. The ancient peoples called the mushroom the “flesh of the gods” and it is believed that the druids used it to come in direct communication with the universe. It is surmised that the druids would consume mushrooms and then sit in sweat houses.
Irish folks have long thought of the mushroom “fruit” as a connection to the much larger organism underground. Because the huge tracts of subterranean mushroom can be thousands of years old, many of the ancients believed that its wisdom could be passed to humans via consumption of the fruit.
SHAMANIC USE OF MUSHROOMS
Shonagh speaks of Mead, a common beverage used also for ritual where it would be spiked with certain herbs and believes that there is a high likelihood that druides included psychoactives like mushrooms in their practices. He says, “The druids trained for 20 years in subjects such as law, astronomy, philosophy, poetry, medicine, music, geometry divination, and magic. It is probable that specific substances were used to induce high trance states to receive poetic inspiration and messages from the gods.” source of info