Here is a link to a fascinating scholarly article published in 1995 in the Journal of Ethnopharmacology entitled "Soma siddhas and alchemical enlightenment: psychedelic mushrooms in Buddhist tradition," by Scott Hajicek-Dobberstein.

The study examines some of the texts of the Tibetan Buddhist tradition, specifically the collection known as the Stories of the Eighty-Four Siddhas, written as texts in the Tibetan language in the 11th or 12 centuries AD from older oral traditions, and describing the lives of eighty-four "adepts" or seekers known as siddha.  

In these stories, the author believes he finds numerous allegorical references to the use of psychedelic mushrooms, including legends of eating cakes of bread balanced upon the point of a needle, visions of a beautiful woman who emerges from a birch tree, but only from the waist up (perhaps to embody the mushroom, which stands only upon one leg and which according to some analysts of sacred mushroom-lore has a symbiotic relationship with the birch tree), and references to beings or demons or deities with only a single eye (also reminiscent of the mushroom, as can be seen in the images above) -- among many others too numerous to list here.

Interestingly enough, Buddhist art from Tibet sometimes depicts bodhisattvas seated in front of a large, halo-like ring which contains wavy radiating lines very suggestive of the underside view of a mushroom cap, with the radiating lines reminiscent of the gills of the mushroom.  The image above (from this wiki) is characteristic of this iconography.  Here is a link to a very beautiful painting from the nineteenth century with similar iconography (click on the "full resolution" link if your browser can handle it). 

Previous posts have mentioned authors and analysts who discuss the prominent presence of mushroom iconography in the world's sacred traditions, including this previous post which links to some articles by Paul Stamets which mention mushrooms in Buddhist art and iconography (unfortunately, some of those articles no longer seem to appear on Mr. Stamets' website), as well as to books which argue that the manna described in the Old Testament may have been meant to describe mushrooms (possibly psychoactive mushrooms).

A very interesting aspect of the 1995 article by Scott Hajicek-Dobberstein linked above is his discussion, beginning in section 4.4 of his piece which can be found on page 114 of the original publication (Journal of Ethnopharmacology 48 (1995)) of the very strong apparent links between the Tibetan Buddhist tradition of Karnaripa/Aryadeva and the Norse god Odin.  

He points out that Odin is constantly referred to by one of his most-dinstinguishing features -- having only one eye.  He notes that Odin gave away his eye in order to gain mystical powers of seeing and wisdom, which has strong parallels to events described in the lives of the Eighty-Four Siddhas.  He also notes that the epithets of Odin found in the Grimnismal in the Poetic Edda include "Long Hood" and "With Broad Hat," both descriptions which could be seen as esoteric references to the mushroom.  Odin often traveled about under a very broad-brimmed hat, something that readers of D'Auleires' Norse Gods & Giants (one of my very favorite books as a child) will know well.  

This connection between Aryadeva and Odin is in fact very profound.  According to the Eddas, Odin became the supreme Norse god by a process of questing for enlightenment in which he hanged himself on the World Tree for nine days and nine nights.  During this time of intense suffering, Odin gained the gift of written language through the runes, which he saw in the scattered twigs at the base of the great Tree.  He imparted this secret to mankind.  

Note that in the ancient Greek myth tradition, Hermes was the giver of language (he corresponds to Thoth the god of scribes and writing in ancient Egypt, a connection which is borne out in many ancient sources and is practically incontestable), and thus Hermes corresponds to Odin.  This ancient correspondence is borne out by the fact that in the days of the week, Odin's Day is Wednesday -- known in the Latinate languages as Mercury's Day (such as miercoles in Spanish).  As Mercury is the Latin name for Hermes, this analysis supports the correspondence between Odin and Hermes (and thus the connection with Thoth).

Interestingly enough, the Buddha is also associated with Hermes according to many scholars throughout the ages.  In this text published in 1904, for example, author John Garnier points to connections between Buddha and Hermes.  He writes:
Buddha is also known as "Heri Maha," "The Great Lord"; as "Datta," "Deva Tat," and "Deva Twashta"; as "Mahi-man," "man" being probably the same as mens, mind, or intelligence, as in "Menu," or "Men Nuh." "Mahi-man" would thus mean "the great Mind," which is exactly the character given to Buddha.  He is also known as "Ma Hesa" and "Har Esa," "The Great Hesa," and "Lord Hesa." 103.
Note that in the mushroom article by Scott Hajicek-Dobberstein, it is Aryadeva whom the author associates with Buddha and with Odin -- the name contains "Deva," which is discussed in the 1904 text.  The names "Deva Tat" and "Deva Twashta" are very linguistically similar to the names of the Egyptian Hermes, Thoth -- also pronounced "Tawt" and sometimes even "Tahuti," or "Djehuty."

John Garnier continues even further, writing on page 109:
Nor is this the only thing connecting Buddha with the Babylonian Hea, who, as we have seen, is identified with the Egyptian Hermes or Mercury.  For the "Tri-Ratna" of Buddhism, which is called "the three precious symbols of the faith," consisted of two serpents twining round a staff (see sketch), and forming a circle and a crescent, symbolic of the sun and moon, in exactly the same way as the "Caduceus" of Hermes or Mercury, the only difference in the Caduceus being that the staff is placed below the serpents.
Buddha, of course, like Odin is associated with the journey towards enlightenment and inner vision.  So these connections between the Buddha and Odin are not at all as alien as they may at first seem.

This subject also invites contemplation upon the connection between the mushroom and the mind, the search for enlightenment, inner vision, shamanic vision, the power of language and writing, the intertwined serpents, the concept of medicine and healing, and many other vital topics.