It looks like William M. was the son of Martha Blanton Heflin based on the 1880 Elmore census. They came from Mississippi, although Martha was born in Alabama. The only Martha Blanton that I can find in MS of the right age was Martha C. Blanton, wife of William H. Blanton. His lineage goes:

Reuben of Rutherford NC>Lewis, SC>John, Choctaw MS>William H.

They are part of the Tidewater Blantons. There is some info on the family in Louise McDonald's work, which can be downloaded from:

www.blantonfamilyhistorians.com

Very little is known about William H. He appears in the 1860 census of Choctaw. However, I cannot find him, Martha Blanton or Martha Heflin in the 1870.

You may also want to test to be certain that you are a Tidewater Blanton before pursuing further research.This is our project website:

http://blantonfamilydna.webs.com/