Members of the 'Cottonmouth' species - which is where they got their name from !
Cottonmouth. Venomous bite.
Cotton mouth
cottonmouth
The Cottonmouth - a highly-venomous species.
Cottonmouth. Venomous bite.
The Cottonmouth - a highly venomous species.
The 'Cottonmouth' - a highly venomous snake species !
Assuming you're talking about the snake's mouth - the species that immediately comes to mind is the cotton-mouth or water moccasin.
A big one. With a big mouth. My wife says maybe bigbird. LOL
Cottonmouth (white mouth). The answer's in the question.
Turtles, Aligators, Snakes, and different types of fish, White owls
If your in the southeastern united states it is most likely a cotton mouth which is poisonous. they also smell like cucumbers.
The Cottonmouth - a highly-venomous species.