I've done some checking.The Lydia Ann Gaddy (1811-1877) who was born in 1811 in Tennessee, married John Franklin George (1805-1888).They lived in Lawrence County, Illinois; and had a bunch of children.
Strange how they both were born in Tennessee and ended up in Illinois.
This Lydia is listed as the daughter of Elijah Gaddy and Lydia Fuller.What strikes me is that your Samuel's middle name is Fuller.
I think it's possible that your Lydia b. 1828 is the daughter of James Marion Gaddy (one of the sons of Elijah Gaddy and Lydia Fuller) and Mary Elizabeth Bass.James Marion Gaddy also appears as James K. Polk Gaddy.
James and Mary Elizabeth, born in Tennessee, lived in Lawrence County, Illinois, and also had a bunch of children.There are a couple of trees both at ancestry.com and familysearch.org