possible family lead for mary brandon of rhea county, tennessee

one of my genealogical brick walls is the ancestry of mary "polly" graves brandon, born 2 aug 1837 in ga or nc, died 23 oct 1916 in harriman, roane co, tn.

mary is buried in an unmarked grave in soldier's circle at the harriman cemetery. her husband david and daughter lizzie montgomery are buried in bean cemetery near white's creek in rhea county. it's a very old community cemetery in really tough shape. one of the leads i keep meaning to follow up are the names of two brandons found on the wpa cemetery listing for the cemetery:

Rachel E Brandon Mar 13, 1844 Mar 30, 1875 31 yrs
Judith Ann Brandon Sept 18, 1824 Mar 30, 1870
Lizzie Montgomery June 28, 1867 Jan 5, 1900 33 yrs. Daughter of D & M Montgomery
David Montgomery Aug 16, 1842 June 19, 1879 37 yrs
[online source for bean cemetery here]