The San Antonio Public Library does have some local high school yearbooks. They are kept in our Texana department. However, we do not have many. You are welcome to call or visit Texana to check if they have the specific high school yearbook you are looking for.
The San Antonio Public Library's number is 210-207-2500. Please ask to speak with someone in Texana. Texana’s hours are located at http://www.mysapl.org/Services/Collections/Texana.aspx
You can also check directly with the high school as they do keep some yearbooks for reference (usually the school library is the best place to start). If these places do not have the yearbook, online websites like eBay or craigslist might have them.