Track down a copy of "Raven a Journal of Vexillology", "Flags of the Native Peoples of the United States" by Donald T. Healy. Published by the North American Vexillological Association, Vol. 3/4 1996-1997. Don & Peter Orenski did a update book, my copy is on loan but I think it as the same name as the original book. Also you will find a link to Don's web site on my link page. Peter also has a commercial web site but the URL escapes me at the moment.
If they survive, the links, the Choctaw, Chickasaw, & Cherokee (Confederate & Union) CW flags have been talked about on this board before as have the Creek & Seminole flags.
Happy Trails!
Tom Martin