Well, after some more searching I think he's a baby black ratsnake.
Here is the description from the Missouri department of Conservation website:
Family:
Colubridae (nonvenomous snakes) in the order Squamata (lizards and snakes)
Description:
Generally shiny black, but some individuals show dark brown blotches. Skin between the scales along the sides may be red. Small patches of red sometimes appear between the scales along the sides. The belly is white, mottled with gray or may be checkered with black. The upper lip, chin and lower part of the neck are usually white. Young are light gray or tan, with dark brown or black blotches on the back and sides. After a year or two of growth, the color changes to a more uniform black.
Pictures of baby black rats, the blotches are a lot bigger than his, so I'm not 100% sure yet. Going to keep looking!
Gale