Looking for Choctaw Native Americans to Assist with Research

My great or great great grandmother was on the Choctaw Trail of Tears 1831-33. Her name was changed to Mary Wallen, Mary Walls or mary Wallis. Her child was Mamie Hamilton, later married and became Mamie matkin.

Mary had an Indian name but I cannot find a record of it. She married a caucasian and to have her accepted, they told everyone she was "half breed," which was not true. She lived for a time in Missouri, near the Ozarks.

Anyone with experience researching native American records or with knowledge of this family member, i would be delighted to hear from you.
We have her photos.

Respectfully,
Kelly