Mississippi State Fund Dollar (aka 'Mississippi at the PPIE'), from the 1915 Panama-Pacific International Exposition in San Francisco. Shevlin SH 18-19.  Tied for the Top Pop with three other pieces. I made one of those three other MS-64's and it is now in very strong, long-term hands, so possibly the best you would be able to locate for any length of time.  I felt that this should have come back RB in which case it would be the finest known; it certainly merits consideration as it is not as 'brown' as most Uncirculated specimens.  Scarce as a Type, VERY Scarce to Rare Uncirculated, especially in certified holders. Many seen are impaired, quite a number holed - to give you an idea of the scarcity of this piece, a circulated raw piece sold for $245 in 2021 on ebay.