Finally, I found a tree on Rootsweb that provided tons of sources, including wills, deeds, and tax records. I'll look to find originals of the records at the GA Archive during my next visit, but because of the numerous records, I am confidant that the tree is accurate and I believe that my DNA match is through the Cash family. (And it doesn't hurt that Moses Cash is an ancestor of Johnny Cash, so it's been very well researched)
Also in the will extract provided for Moses Cash was a mention of another daughter, Sara, wife of William Craft. This sounded familiar - and it should: this couple was also in my family tree. I had a listing for Sarah F Cash, wife of William Jasper Craft. After more research, I'm confidant that Sara and Elizabeth are sisters, the daughters of Moses and Nancy Cash.
This connection creates yet another instance of Pedigree Collapse in my tree. I now have two sets couples who are my 5x Great-Grandparents twice over. In order to see these connections, I like to sketch out the tree, which you can see below: