According to the BBC, the shamans of the indigenous Sámi people of Lapland consumed small amounts of Amanita muscaria in their visionary rituals and drank urine from their reindeer, who eat the iconic red-and-white mushroom as part of their diet and metabolize its toxins without harm, excreting a fluid still full of psychoactive compounds but free from toxins. One of the known psychedelic effects of Amanita muscaria on humans is the sensation of flying, which might explain the origin of the myth about the man clad in red and white soaring through the sky on his reindeer-drawn sled, dispensing tokens of love to the world.
A decade after the BBC first brought this speculative theory to the popular imagination, filmmaker Matthew Salton set out to reenvision Christmas as a celebration not of capitalism but of shamanism in a wonderful op-doc for the New York Times, lensing the theory through the work of two scholars — Boston university classicist Carl Ruck, who studies ancient shamanistic traditions and ecstatic rituals, and mycologist Lawrence Millman.
https://vimeo.com/248496167?embedded=true&source=vimeo_logo&owner=5619280
For more on Amanita muscaria and its chemistry, its cultural myths, and its scientific promise, ethnobotanist Rob Nelson of Untamed Science has an excellent (and beautifully cinematic) primer:
--Maria Popova