I think at least one of the names of psilocybin mushrooms somewhere is a variant of Saint Peter. You already probably know the popular, easy to grow tropical cactus that bears the name. And then there is the "vine of death" which is a distinct "saint peter" reference (as in the gatekeeper of the heaven).

Mushrooms are extremely interesting. I definitely agree with McKenna that they were the most likely first psychedelic ever used by humans, because they just grow. I don't think that they prompted the evolution of language though, that is a natural step you can see in many birds, especially, with their songs and tool using. DMT takes you further but psilocybin has this way of showing you the future that is distinct.