I'm not sure about the terrain and/or the vegetation in that part of TX, but if it involves clusters of prickly pear cactus, you will find rattlers nestled in them.
When I used to catch snakes, I used a snake stick which was made of an old broom or mop handle with a metal hook on the end. Hook the snake about 1/3 of the length of his body. This is a natural balance point, in that the head and first 1/3 of the body weigh about the same as the 2/3 that includes the tail.
When you hoist him up off the ground, you should have a helper nearby holding a "tote sack" (burlap bag), open. Dump the snack into the bag (one snake per bag), then twist the opening of the bag (quickly) closed. Then tie an overhand knot in the neck of the bag.
To kill a snake without cutting, shooting, or otherwise damaging the skin, simply place the bagged up snake on the dashboard of a vehicle, then close the windows and doors. The heat will build up in the vehicle, thusly killing the snake by overheating. (hyperthermia?)
Never skinned one out, cooked one, or ate one - so, can't help you there.