This is a finished reverse die trial, in white metal, of a Heraldic eagle. According to Pollock, it was made by Anthony C. Paquet for Dr. J.T. Barclay on July 6, 1857.
It exists as both die struck and cast varieties. About 5 are known according to Judd.
For additional information on these, please refer to the article on the 1861 Paquet dollars in the ANA Centennial Anthology.
Photo courtesy of American Numismatic Rarities.