A Common Musk Turtle very nearly hidden in the leaf litter at the bottom of Dixon Branch at White Rock Lake, Dallas, Texas.

Wikipedia has this to say about Common Musk Turtles:

Sternotherus odoratus is a species of small turtle native to southeastern Canada and much of the Eastern United States. It is also known as the common musk turtle or stinkpot due to its ability to release a foul musky odor from scent glands on the edge of its shell, possibly to deter predation.

Common Musk Turtle - Hidden
Common Musk Turtle - Hidden