Pituophis catenifer (Bullsnake).

Wish it was living in my yard! Gophers wouldn't be happy.

The critical part - for AZ - is the smooth tapering tail.

Nothing of that coloration in this state is venomous unless it also has rattles on the tail.

Good rodent control, will not bite unless you pick it up and hassle it.

Nice one! I was thinking bull snake but I'm far from an expert so I'm glad others who are more knowledgable about snakes chimed in. Either way I just wanted to say great pic and that I'm jealous! My little garden gets a lot of pocket mice and this dude would be well-fed here, hah. Thanks for the neat pic. Happy gardening!