Some online family trees list this Presley Jennings as the son of John Jennings (1706-1760) and Ann Burton (1712-1779) of Orange Co., Virginia. I find it a bit unlikely that Ann would be having children at age 52. Also, there is no evidence that (that I know of) that any other children of John Jennings and Ann Burton were ever in Grayson Co., Virginia, whereas all three proven children of Jonathan Jennings and Dianna Bobbitt settled in Grayson County. So I find it more likely that he is the son of Jonathan Jennings and Dianah Bobbitt, who are a better fit for both age and location.

But since I know of no actual evidence for either attribution, his parentage should be considered tentative.

1830 census of Grayson Co., Virginia, lists on p. 39:
Jinnings, Presley, 1 male 60-69; 1 male 15-19; 1 female 50-59; 1 female 20-29; 1 female 15-19.

1840 census of Grayson Co., Virginia, lists:
Presley Jennings, 1 white male 70-79, 1 white female 60-69; 1 white female 15 to 19; 2 male slaves, 1 10-23 and 1 36-54.

1850 census of Carroll Co., Virginia, p. 113, lists as family #819:
Pressley Jenings, 86, farmer; Nancy, 80; Christina Dunford, 23.