It appears certain that Pleasant Childress/Childers, Senior (a close relative of Mosby Childers, as proven by DNA testing) married Sally Jeffries, a daughter of Nathaniel Jeffries. Also, some show that the Elizabeth Jeffries who married Mosby Childers was only related to Nathaniel Jeffries in some close way....but she was APPARENTLY not a daughter of Nathaniel Jeffries (as I recall, no daughter named "Elizabeth" was mentioned in Nathaniel Jeffries' Will).
By the way, I am not convinced that the John Brown (supposedly born 1775-1780) who married a Lucy Jeffries (out of Swepson Jeffries) was definitely a son of Thomas Brown and Mary Pettus of Lunenburg/Mecklenburg Co., VA after all. It seems that the children of Thomas and Mary (Pettus) Brown were born closer to the 1750s or so. Perhaps that John Brown was instead a grandson of Thomas and Mary (Pettus) Brown....but no proof.