I thought your query was for living people, but after looking at the query you posted on the Rust forum, Marshall and Sallie were married in 1883, so more then likely their children were born soon after that, and probably are deceased.
Combined info from TX Dth Idx Online and SSDI:
Will E. Rust, b 16 Jun 1899; d 20 Jun 1976 Potter Co, TX; last residence Amarillo, Randall Co, TX; SS card issued in TX.
On your other query from Rust forum you listed among the children a "Willie".If he went by Willie there are several "possible" matches on the TX Dth Idx Online, you might want to check them out.Then you could post a query on the county site where he lived and died.Be sure to check the GenWeb site for those counties, too.Many GenWeb counties are putting their cemeteries online. http://vitals.rootsweb.com/tx/death/search.cgihttp://vitals.rootsweb.com/tx/death/search.cgi