I am not related, but have some information on these Raineys.
Luther was the son of William Lesley "Mandy" Rainey 1873-1948 and Minerva Bennett 1883-1930. "Mandy or Manny" Rainey was the son of Charles G. Rainey-Civil War Veteran 1839-1905 and Salena Luvica "Vica" Walker 1851-after1920.
Minerva Bennett is said to be the daughter of Edward Coatly Bennett and Eliza Mashon. The Bennetts and the Mashons were part Indian.
By 1940 Luther was married to Thelma Louise Smith - with no children.
I don't know what he did between 1940 and his death.