I remember on a video that the RRS linked to on google video, It said that when the bible refers to "heavenly manna" it was meaning halucinogenic mushrooms and that the person who wrote the book of revelations, was in a place known for its abundace of these mushrooms. furthermore, it also showed pictures of Rabbis or somesuch with a headdress that was in the shape of a mushroom to symbolise the manna and that the popes hat is of the head of a fish (the split down the middle being its mouth), the fish being pisces. the video may just be making unsubstantiated claims but they do make good sense and seem well researched allthough some seem to be stretched somewhat. I'll have a look for the video again and edit it in to this post if I find it.

edit: I found the video but it seems to have been removed from google video (link)

The ergot theory keeps coming up for Salem, but it's not consistent with the whole 2+ year-long story of what happened.  A much more plausible and simpler explanation for the Salem incident is conversion disorder or somatization disorder, which can sometimes spread through groups of adolescents living in close quarters.

Similarly, people's brains are perfectly able to produce all kinds of altered states of consciousness without any chemical assistance at all.  Ergot or other psychoactive substances are a possible explanation for some experiences, but they aren't necessary.