Is this one your own copy ?
Unfortunately, no. I found it during a web search about the Tatham Stamp & Coin Co. There were apparently several "denominations" in different colors made as promotional pieces. Here's an eBay
listing for this one ... $4.95 is the "buy it now" price or else wait for the 26 days left to their auction.http://www.ebay.com/itm/Tatham-Stam...t_541wt_1110
Quite an interesting story behind that stamp company, though, as being a native of Massachusetts, it was particularly interesting. Come to think of it a number of stamp collecting facsimiles, bogus and/or counterfeit stamps originated in this area of the US, so I guess I'll have to keep a sharp lookout for such things!