Gopher snake

I agree with the ID of Pituophis catenifer, Gopher Snake. They are excellent Rattlesnake Mimics, and can flatten their head to make it look more triangular. Then they rattle/shake their tail, so if it's in small rocks or leaf litter, it almost sounds like a rattlesnake. If that doesn't work, they can hiss quite loudly, both during the inhale and the exhale, for a nearly constant sound. Most are laid back, and won't bite without a few warning headbutts and the aforementioned hissing. The Sonoran subspecies (P. c. Affinis) can get up to 92", though most found are 48" - 60" long.