I solved my own question! I asked the Tennessee Archives to search the TN Athens-Post for the date in question and they just sent me the clip from 1856 Athens Post of TN (they initially said, we don't have Georgia newspapers...I said, I know, but I think the reference in the book is wrong...it must be TN, not Georgia.. The article says briefly "On the 17th ult, by Rev Z. Ross, Mr. J.A.Gwinn to Miss Nancy A., daughter of Wm. Kimsey, Esq., all of Polk County."
Interesting that Guinn is spelled Gwinn and the "Esq" after William's name. I will post the clip on my public tree in case anyone else ever wants it!