Map turtles in general have a lot of identification challenges, but the yellow pattern on the head behind the eyes, the way that some of the yellow lines on the neck reach the eye, and the dark gray spots on the carapace lead me to believe that this is a Ouachita Map Turtle (Graptemys ouachitensis). This species is bred annual in captivity by several commercial aquatic turtle farms and as a result it is readily available in the pet trade.