Calvin's father may be Lee Wesley Graham, who died in Houston, Texas, after receiving a head injury from a car accident in November 1940. If Calvin joined the armed forces in 1942, "after his father had died", this may be a piece of the puzzle.
It appears that Calvin is descended from Samuel Houston Graham and his wife Mattie Patton. Under a different heading, WikiTree volunteers are being asked:
Should Lee Wesley Graham Graham-17207 be merged with Graham-12843?
Hope this helps!