Ah, I looked it up and accepted "rye bread" without actually reading the name of the fungus, so you're probably right about that part.

The broomstick myth that I've heard does indeed involve substance abuse to achieve an altered state of mind. The broomstick specific part was because apparently some women would put the substance on the end of a broomstick and apply it, shall we say, internally, thinking that this would achieve greater (or perhaps faster) effect. I don't know whether entheogen was the material in question.

As initially mentioned, I make no claim that this is true, only that I read it a long time ago and never really questioned it.

edit: Forgot to thank you for the clearly knowledgeable response!