I have made a handy dandy picture comparing 8 north american rat snake head patterns and saddle patterns. I'm sorry that the yellow rat is a bit older than the others. People apparently don't like to post clear pictures of baby yellow rats. But it's still clear enough.
1 & 2- Typical corn snake head pattern and saddle pattern. Note the complete central pattern that is typically present unless there is a pattern modifying gene present such as masque, stripe, or sunkissed. Of which the OPs snake is not one of. Also note the generally rounded bottom edge of the saddle. This is fairly typical but saddle edges can be more square, uneven, or slightly peaked in non-banded individuals.
3&4- Black rat. Note the near absence of the central part of the head pattern and very narrow brow band. Also note the strong downward peak to the saddles. There is of course variation, but this is typical.
5&6- Gray rat snake. Almost absent head pattern. Saddles small, spaced far apart, and deeply scalloped.
7&8- Yellow rat. Almost absent head pattern. Saddle margins deeply scalloped and pointed.
9&10- Baird's rat snake. Brow band present. Central pattern mostly absent but better defined than on a black rat. Saddles are very narrow.
11&12- Emoryi rat snake. Head pattern and saddles are very much like a corn. However, head pattern typically extends onto the neck, often resulting in a couple paired blotches of saddles.
13&14- Texas rat snake. Brow band present, but central head pattern primarily absent. Saddles are similar to corn with a slight downward peak. There is variation, but this is typical.
15&16- Eastern Fox Snake. Present head pattern, but unlike that seen on corns. Saddles are broad and often squared off, frequently alternating with the lateral patterning in an almost checkerboard fashion.
Now. The snake posted by Ninabeena is lacking most of the head pattern, and has rather strongly scalloped edges to the saddles, especially on the first third. These saddles and the head pattern most closely match that of the gray rat, and the yellow rat. However, as Nina said that it's getting yellow, that rules out the gray rat leaving the yellow rat snake as the most likely species of this snake.