Is Yancy the maiden name and Stone the husband's last name?
Would you know the county and or city in VA where she was born?
Per www.familycentral.net/index/family , there was a Phoebe Yancy Stone born in New Kent, VA about 1734. Parents shown as John Wilkes and Mrs. John Wilkes.
There was also a Phoeb Yancy Wilkes (Stone) 1742-1785.