Dear Ms. Welborn,
Thank you for posting your request on History Hub.
While NARA does not keep a record of burial grounds, I have been able to locate a few resources which may be useful for you.
For information on any possible Indian burial ground, you may with to reach out to the Texas Historical Commission.
More information on the Fort is available at the Texas State Historical Association.
Be aware that burial sites are protected under the State Antiquities Code
We hope this is helpful in your research.