The folks over at NPR’s Planet Money have a great piece today on the stash of unused dollar coins that’s piling up at the Federal Reserve. Back in 2005, Congress passed a law ordering the Fed to mint a series of dollar coins honoring the presidents. The plan was to wean Americans off paper bills. It hasn’t exactly worked. There are currently about 1.2 billion dollar coins sitting unused in Federal Reserve vaults. The program has cost $300 million so far, and is scheduled to run through 2016.