The hallucinogen in amanita muscaria is the only hallucinogen that is NOT metabolized by the human body and just goes right out in the urine. It may then be used by another devotee.
The Sa'ami in the far North of Scandinavia, used it in pursuit of visions in their old religion. The Apostolic Charismatic Church of the First Born in the United States, where it still uses a narcotic as a sacrament, uses peyote.
Try: http://www.evilchili.com/mediaview/4588/Swedish_Midsummer_Feast for a recent video on the situation.
It was processed through animals as well; reindeer in northeast Asia and cattle in India (sacred cows).
A lot of these details are in R. Gordon Wasson's writings.