Corn snake

They are often mistaken for venomous copperheads.

An excerpt from the article 21 facts about corn snake
Corn snakes are brighter and more slender. Adult corn snakes typically have large red-blotchy patterns outlined in black on gray, orange, or yellow skin, while young snakes lack brightness. They are also distinguished by the black-and-white pattern on their underbellies, resembling a checkerboard.

The main difference, making them easily distinguishable, is that copperheads’ pattern is hourglass-shaped.