It was the oval shaped flat headed two-pronged tack for the "tacked headed" toms that I was referring to that were hard to find (photo here).
The tacks that Kevin is referring to here in this post are the center pins from the Gretsch Tom badges. They are not hard to find...I just bought a bag of them on eBay and tacked a 16" Gretsch floor tom with them - only because I could not find the flat-headed oval tacks at that time. I since bought a 1920's Gretsch Chinese-type tom (both heads tacked) and salvaged the tacks (for another project).
For instance a brand name - or model - similar or almost the same as the Gretsch center pins is Daisy Antique and they're simply a type of upholstery tack.