Austin History Center - Our local history archives. See the the "subject guides" under the "Research" section for more about collection of interest to this project.
Google Books - Search the full text of current and historic texts. Reference to some Texas schools might be found in local and Texas history books.
Texas Archival Resources Online - A catalog of finding aids from archives across Texas. Most of this material hasn't been digitized, but you'll get a sense of which local archives may be worth visiting in person.