1921 Missouri Centennial. Plain. MS-66 (PCGS).We are pleased to be offering multiple premium Gem examples of the conditionally challenging Missouri Centennial half dollar in this auction. The coin featured here is richly frosted in finish with only a few blushes of russet and olive-gold precluding full brilliance. Boldly struck, expertly preserved, and sure to please even the most discerning numismatist.