That is a yellow mud turtle (Kinosternon flavescens). It's easy to tell muds from musks by looking at the plastron: Kinosternon have a large plastron with two hinges and triangular pectoral scutes (the scutes in front of the anterior hinge), so the seams around the pectorals form a 'K' shape. Sternotherus have a smaller palstron with only one hinge and quadrangular pectoral scutes. They also tend to show a lot of soft skin along the seams of the plastral scutes.

K. flavescens and the Mississippi mud (K. subrubrum hippocrepis) both occur in east Texas. The Mississippi mud is darker over all and has light facial stripes like a stinkpot.