Thanks Joe.Your info about John Tillman was new to me.How did you find he was Rebecca's son? Sure seems true. Here's what I know about him:A John Tillman Mullis was living in the home of Joseph Mullis in 1860.He was 8 years old.The reference is USCensus, Pulaski County, GA, 1860; page 291, dwelling #351.
On the 1870 census, Elbert, age 21, was living in the home of Newton Mullis.Also, a "John", age 16 (John Tillman??)This reference is USCensus, Pulaski County, GA, 1870; page 140-141, dwelling 1158.
About the Elbert in North Carolina, I doubt he was the one I'm interested in.I've found several Elberts in Georgia after 1870 but cannot pin them down.
I claim Berry is a son of William and Nancy Quinn Mullis because the 1850 census shows several of them living in adjacent houses--William in dwelling 207, Jesse in 208, Joel in 209, Noah in 210, and Berry in 21l.
Also, William's offspring are listed in Barbara Culp's MULLIS MELANGE. There were others besides those named above. I don't know where Barbara got her information.
Berry disappeared between 1850 and 1860. He may have died, as you think.Sure wish I could find some proof.