These are obverse die trials, struck in white metal outside the mint, from an 1806 die with pointed 6 variety sold by the mint as scrap. Stacks calls this obverse the same as the one used on Overton 123 & 124.
The Pollock book mentions a notation from Abe Kosoff saying that they were struck by David Proskey. About a half dozen are known.
At least 3 other examples are known with a reverse using an embossing die for a 12 cent stamp featuring a portrait of Henry Clay of which one is struck on a spade shaped piece of metal. These latter pieces are listed as JA1806-1/P6150.
The die itself is still extant and is in the American Numismatic Society.
The image is a scan from Heritage's 1985 ANA sale.