Western ribbon snake (thamnophis proximus) and common garter snake (thamnophis sirtalis), practically the same thing. I associate the dot on the head more with the ribbon snake but some garters have that, I think. The ribbon snake's scales may be more heavily keeled, and garter snakes will achieve a longer length. This species is immune to toad secretions. I wouldn't advise it, but there is a lot of pet trade in both kinds of snakes, with garter snakes making the better pet. Glad you didn't panic and blow it out of the water, cause both types of snakes are harmless. (My son does herpetology research and is better at that than me; I try to stick to western Oklahoma plants)