This is the Gold Chrome version of Herschel's #51 card in the 2005 Topps All-American set, featuring college greats.
Walker has at least 18 cards in this set, including autographs, refractors, xfractors and super fractors. Not to mention, printing plates.
I currently have six of those cards in the Hoard, including three autographed.
The gold chrome, like the regular chrome version, is serial numbered to 555, which you'd think would make it easy to find. However, I have not seen the gold chrome until recently.