Lake Texoma fishing license:
(cost $12) bought state wide in Oklahoma or Texas it's valid through the calendar year
Raingear:
Top and bottom (NOT a poncho) windy days will get you very wet with the overspray.
Warm clothes:
Bring plenty, you can always take them off if you get hot. Dress for the low temp of the day not the high.
Water proof boots:
If you don't like wet or cold feet
Ice chest:
For snacks on the boat and to pack your fish on ice for the trip home
Camera:
Hopefully to take a fish picture!
Sunscreen:
Especially in the summer months
Sunglasses:
Water has a glare on sunny days