Yesterday we stopped by our PO Box on Canal Street to pick up our mail. In the box was a cookbook mailed to us for review, some checks from advertisers, a couple of invitations to local events, and a mysterious white envelope with no return address. It felt heavy, and overcoming a strong fear of anthrax poisoning, we opened it to find a second envelope, containing a third (plastic) envelope, containing a coin in a plastic case. The coin had Banksy images on both sides: his classic rat on the front, and his ape on the back (or vice-versa: it's not clear which side is the obverse, which is what coin collectors call the front of a coin.)

We need help solving this mystery. Did Banksy send us this coin? We know he's printed money before, but no one seems to have mentioned him making coins. If it wasn't him, who sent it, and why? And what are we supposed to do with it? It says not to sell it on eBay, and to trade it for goods or services—but which goods, and what services? We are open to your ideas!

Update— an anonymous emailer writes: "I got one too! I answered an ad on Craigslist, got a reply, and met a guy by MOMA, he handed me two. The e-mail said to keep one and leave the second in a public place. I left mine in Union Square."

Update: Banksy's publicist sent us a note: "The coin is not by Banksy. Thanks! -Jo" We've asked if Banksy has any ideas who or what is behind it, and how he feels about people making money with his name on it. We'll let you know if he responds!