I am trying to find the Native American connection on this side of my family.
My Great Grandmother is:
Maudie B Mills
Birth 7 Nov 1899 in Wister, Le Flore, Oklahoma, United States
Death 23 Apr 1980 in San Antonio, Bexar, Texas, United States

I was always told that her mother was full blooded Indian so I'm trying to prove this in my tree.

These are her parents:
William Oscar Mills
Birth Sep 1871 in Nodaway County, Missouri
Death 1918 in Wister, Le Flore, Oklahoma, USA

Lou Cindy Kieffer (or Kiefer)
Birth 7 Nov 1881 in Arkansas, United States
Death 14 Oct 1949 in Riverside, Riverside, California, United States

The Native history could have come from either side. I've checked the rolls but it's hard to make sense of any of it.

Any help would be greatly appreciated!