The buffalo headed man shows up several times in Shadow's dreams throughout American Gods. I find it important to mention the symbolism of the buffalo headed man in relationship to out main protagonist because the Native people of this land were the original American's. Everyone else who lives here immigrated from somewhere else. I also believe it was important for Gaiman to represent the original peoples of this land in this novel.
There are many times throughout the book when Shadow is portrayed as a Shaman. In chapter 5, Wednesday tells Shadow to, "Concentrate on making those clouds-the ones over there, in the west-making them bigger and darker. Think grey skies and driving winds coming down from the arctic. Think snow" (97).
It is well known that Native American Shaman's would do prayers, ceremonies, and dances to call for rain. In Shadow's case, it worked. The clouds came in and the snow came flurrying down.
There are also several times when Shadow can hear people's thoughts. One time in particular is when Wednesday and Shadow are going to an Indian reservation to meet with Wisakedjak, an old Algonquin God. They are walking in the desert and Shadow accidentally stumbles and falls onto some bones that look like they are set up as part of an altar or ancestral honoring place. When Shadow accidentally touches the bones, he begins to have a vision that they are being pursued by the henchmen of the new Gods, Mr. Town. Shadow is all of a sudden in Mr. Town's head and can see everything he is doing and hear everything he is thinking. If Shadow were not a Shaman, nothing would have happened when he touched those bones.
Almost every time Shadow dreams, he dreams of a tribe of people out on the plains of America. Or, he dreams of the buffalo headed man speaking to him telepathically. In native folklore, the buffalo headed man would be Shadow's spirit guide. Even Shadow's name implies that he is able to walk in the spirit world, a shadow walking between the spirit world and the tangible world.
During the same trip to the desert to see Wisakedjak, who is called Whiskey Jack by Shadow and Wednesday, Whiskey Jack asks Shadow to tell him of his dream, and of the buffalo headed man. After Shadow tells him of his dreams Whiskey Jack says, "When you find your tribe, come back and see me. I can help." Shadow replies, "I shall"(312).
Shadow picks up a character named Sam Black Crow who is hitchhiking along the road to Cairo. When he picks her up she asks him a bunch of questions about himself. One of the questions she asks is if he has Indian blood in him. "Not that I know of." Shadow replies. "You looked like it was all" Sam says. (148) Sam informs him that she herself is half Cherokee Indian.
Again and again we can see the signs pointing to Shadow's Shamanic abilities and connection to tribe. The symbolism of the Native American element in this book is well represented through Shadow's character. It is not clear if Shadow ever realizes fully his Shamanic abilities, but it is clear that he has them.