Brigadier General Richard B. Mason was the first military and civil governor of California. He died at Jefferson Barracks while he was the commanding officer there. After his death, his widow married Major General Don Carlos Buell, a veteran of the Union Army. 

Both generals, and their wife, Margaret Hunter Mason Buell are buried on the same lot. Marking the grave of General Mason is a brown freestone memorial made in Philadelphia by John Struthers, the man who designed the marble sarcophagus in which the remains of George and Martha Washington repose at Mount Vernon.