My mother suggested that she had seen a letter indicating that Julia Ann Thornton was 1/4 Indian. At some point, someone even mentioned Pocahontas! I looked in the 1985 edition of the book Pocahontas' Descendants; although there were several Thorntons in there, I didn't see anything I considered to be evidence of a familial link.
Virginia Thornton of Tazewell County is included in a list of Civil War pension applicants at http://www.rootsweb.com/~usgenweb/pensions/civilwar/:
-------------------------------------------------------------------------- Description State/County of Application or Residence -------------------------------------------------------------------------- . . . . . Virginia Thornton, widow Tazewell . . . . .
I believe that the full pension applications are available somewhere.