(serious) prehistoric use of fungi

[FRED]

I'm trying to find information on how our ancestors perhaps used fungi in 
their lives.
I've come across a few cases, such as the man in the ice near Austria found 
recently, but I want more than just one photo and a paragraph.
The medicinal side of things is an interest of mine, but I would love to hear 
of any leads investigating the ritual use of psychoactive fungi within 
these cultures.
I'm studying Archaeology at Bradford, and I would like some serious feedback 
and not just opinions on 'cool trips' and the like.
Ta.