Collectible coins include various types such as commemorative coins, historical coins, and bullion coins. The United States has a rich history in coinage, with notable pieces including the Twenty Dollar Gold Coin, commonly known as the Double Eagle, and the Flying Eagle Cent, released in 1857. The Flying Eagle Cent, struck in Philadelphia, is particularly sought after by collectors due to its historical significance and unique design. Collectors often look for coins in high grades and specific mint marks to enhance their value and desirability.