Hello LeAnne -
I don't know how much information you have. I believe that William Green Mitchell is the son of Willie Mitchell, who is the son of George Mitchell, US Rev. War Soldier. George received a land grant in Johnston County, between Rains Crossroads Church and Pinckney. That land still belongs to the Mitchell family. George, WG and Patience Mariah, (known as Pasha in her lifetime) are buried on that land near the intersection of Rains Crossroads Church Road and Hickory Cross Road. The cemetary is in a field behind a house and cannot be seen from the road.
William Green Mitchell and Patience Mariah are my GGGrandparents also. Your GGrandfather, Allen Walter Mitchell is brother to my GGrandfather Leonard Earl Mitchell. There was also a brother named Charlie who married Addie and another named Ed.
I'm hopeful this is helpful to you. Good luck. Please keep in touch.