Herschel Walker Signed Autographed Dallas Cowboys Best Wishes 8x10 Photo. This licensed Photo has been signed by Herschel Walker. The autograph has been certified authentic by PSA/DNA and comes with their authentication sticker and matching certificate of authenticity that can be verified online. PSA/DNA is the leading third-party authenticator in the autograph industry. This signed Photo is a great gift idea for any Dallas Cowboys fan or memorabilia collector. Commemorate the great career of Herschel Walker with this Photo and check out other memorabilia at Prime One Sports.com.