I have a different family line. My ancestor was Usley Gragg, born about 1819, the daughter of Robert Gragg and Rhonda Majors. She married Charles Farr 1834. By 1850 Usley had died and Charles married her widowed sister. This family was living in Clinton Co., KY in 1850.
I have in my files some copies from "Gragg Descent" by George Robert Gragg, 1978. I don't see a Usley Gragg just glancing through it. But I will try to read it tomorrow and let you know if I find anything that might help you. I think my sister found this and I have not really had a chance to read it through and through. I use things like this as clues. We have many more resources now that we had in 1978 when this was written. There is several Roberts mentioned and one of them may be yours. I will be back with you as soon as possible.
Debbie I read the paper carefully last night. I also found a note from my sister wanting me to read it to see if it pertained to our Gargg family. It does. She had just copied selected pages and you may want to find the whole book and read it. I'm sure she found it at Clayton Library in Houston, as that is where she goes to research. The Name is "Gragg Descent" by George Robert Gragg, 1978. It has no publishers name on it and I think it may have been self published. If you don't live near a big library ask your Librian to order it for you through the innter Library program. This family was in Augusta, VA and then to Tenn. Our Henry wound up in Missouri, where one of his daughters Martha Jane married William B. Magill. Sorry I could not help.