This is the unique die trial for the 1935-S with small 1934 above the word Pioneer variety Daniel Boone commemorative half. Pollock lists this with a plain edge but it actually has a reeded edge.
It is believed to be unique with the only specimen being in the collection of the American Numismatic Society. To my knowledge, this is the first time this piece has been illustrated and made available to the collecting fraternity at large.
A listing for the Philadelphia mint version of this design without the 1934 above the word Pioneer J2040/P2071 has not been confirmed and may be a misdescription of the above piece.
Photo courtesy of the American Numismatic Society, accession number 1951.127.3.