In Greece centuries ago, some people mixed ergot extract in a drink and tripped together, and worshipped the ergot. Hence a religon based around a chemical v similare to LSD.

The visions produced by 'soma' (now largely regarded as the Fly Agaric mushroom, Amanita muscaria) are thought to be the foundations of Hinduism. I mean Shiva and Ganesh are both the typw of trippy things you would come up with when tripping on shrooms.