I'm looking for two types of books:
Books on the pre-Columbian contact Indians in the United States, Canada -- how they lived, how they farmed, their mythology, etc. Or, in general, if anyone has a good book on indigenous religion in North America, that would also be much appreciated!
Books on how the Plains Indians tried to cope with with being displaced from the lands, Indian wars, etc.
I would take a look at our book list first.
Elliott West's The Contested Plains addresses your second question, at least concerning the Cheyenne and the southern Great Plains.
A good book on Native religions is Peter Nabokov's Where Lightning Strikes. As he says in his introduction (which you can read above), "This book focuses on relationships between Indians, environments, and religions," and does so over the course of sixteen case studies, each involving a different tribe.
I would definitely highly recommend The Middle Ground and Custer Died for Your Sins from the reading list but also check out Playing Indian by Phil Deloria (Vine's son). He shows how the idealized "Indian" in American popular culture, stretching back to the American Revolution, has never necessarily been in sync with the realities of U.S.-Indian relationships or Indian life.