Collectible coins, such as those from the United States, include various types like state quarters and commemorative issues. The 25-cent coins, especially those released in Mint Sets, are often sought after by collectors for their quality and limited availability. The 2015 Mint Sets, which contain uncirculated examples of that year's coins, feature designs that celebrate notable American themes and historical figures, making them appealing to both numismatists and casual collectors. These sets can enhance a collection and hold potential value due to their condition and official packaging.