Your John was a Jr. According to both my elders' oral tradition, and the internet (so it must be true!) Isaac Berry had one son, John (Sr.). John had three sons: John Jr., German, and David (1770-1831). David is my ancestor through his son German. So John Sr. is our common ancestor.
I was born in Louisiana also. Also in Louisiana, there is a doctor named Gene Berry (about 65 years old) who is a friend of ours. His family is from Mississippi but we never made a specific connection.
I found the story below, which is consistent with my elders' tales, at the website below. It has links to many people in the your chain. http://www.barlowgenealogy.com/MsKinfolk/Berry/JohnBerry1.ht...
The Berry family came to America in the 1600's, and settled in Virginia. Some of them settled at Whitehall, Virginia; were prominent citizens there, and established the first Episcopal Church there. John Berry lived in or near Richmond, Virginia.