Hard to say for sure with the pic taken from the next county, but the pattern doesn't look quite right for a gray rat snake. I would guess that it's an immature pine snake.
Did a little reading up on the mud snake. One article said they’re not often seen as they tend to hide in aquatic vegetation. Guess I was lucky to see this one. He didn’t seem shy, made no effort to retreat while I took the picture. The ditch he was in is full of frogs, guess he was more interested in lunch.