I've had several emails and calls asking about getting a Texas license online, here's the link: http://tpwd.texas.gov/business/licenses/online_sales/
There's a $5 admin fee for buying online. If you don't want to pay it, there's a Walmart in Marshall off Highway 43. Costs: Non-resident freshwater annual = $58+fee (valid until Aug. 31, 2016)
Non-resident all water daily = $16+fee (valid on day specified, only)
65 and over, who possess a LA resident fishing license, are not required to purchase a TX license. Also, non-resident under 17 years of age are not required to purchase a TX license.