Half dollars that sold for a dollar but are priceless to me

The Columbian Exposition half dollar was sold in 1892 and 1893 for $1 each to raise money for the World's Fair in Chicago IL. 2.5 million were distributed to the public but not all of them were sold; the extras were released into circulation for their face value. This half dollar was the first commemorative coin for the US by having Christopher Columbus on it. Most coins during that time had Lady Liberty on them, not a physical person. The coin features the date 1492, 400 years before the coin was minted and when Columbus “discovered” the New World, and it features the Santa Maria.

My great-grandma, who lived in Illinois, acquired one of them and she gave it to me when I started coin collecting. She had left it stuck to the bottom of a can which is why there are yellowish spots and a few scratches on the obverse. The damage brings the coin’s value down to $15 but I will never sell it because it was a priceless gift from my great-grandma.