Do you have names to go with the initials of W.A.?Have you tried the Van Zandt Co, TX GenWeb site?Some GenWeb counties are putting their cemeteries online.Do you know when W.A. died?If so, obtain a copy of his death certificate.
Info from TX Dth Idx Online, & SSDI: Robert W. Gammon Sr. b 5 Jan 1904, d 14 Oct 1970, last known residence Dallas, Dallas Co, TX & Soc. Sec. # was issued in TX.
SSDI has another Robert:Robert Gammon , b 25 Jun 1924, d Jun 1975, last known residence not given, SS # issued in AZ.Not shown on TX Dth Idx Online.
TX Dth Idx Online gives another Robert:Robert W. Gammon II, d 4-06-1975 in Dallas Co, TX.Not shown on SSDI.