This website is very useful. http://www.tshaonline.org/handbook/online It probably has more information than you need :)
We took a lot of field trips--Austin, San Antonio, Houston. We live in Huntsville so there is a lot of TX history here as far as Sam Houston is concerned(as well as the Sam Houston Folk Festival--that is at the end of April/beginning of May).
We watched the Alamo w/John Wayne(It's not exactly accurate, but a good movie none the less) and another movie about Stephen F Austin. I can't remember the title.
There are so many books, movies, documentaries, hands-on field trips available when you study Texas.
Oh, don't forget Washington on the Brazos. There is also Barrington Farms in the same area that allows you to come and work on an early Texas farm.
We also read Old Yeller and Savage Sam. Fred Gipson is from Mason Co. TX. The library there has a statue of Old Yeller.