HK-15A, struck for the 1870 Pilgrim Jubilee celebration to commemorate the 250th Anniversary of the landing.  Choice Uncirculated, certified NGC MS-64.  36mm, struck in Copper and Gilt (Gold Plated), by Scovill Manufacturing of Waterbury, CT.  HK-15 as listed in HK as "Brass" may not exist per se, as all examples have been certified as "15A".  Scarcer than the Silver-plated version (HK-13), by a wide margin - the unplated Copper version is the rarest composition other than a couple of odd-ball White Metal pieces known, likely struck to Scovill's own account.  R-5 in the Second Ed of H-K, the average Unc grade tends to be 63/64, with very few finer.  Not too commonly seen, with the last ebay sale I could find back in 2023 (MS-63 at $350).  Previously, in Jan. 2022, one of the 5 NGC MS-65's sold at $600.  Priced somewhere in between.

NGC 8900590-001