Collectible coins, often sought after by numismatists, can include various types such as historical coins, bullion coins, and commemorative issues. The United States of America has issued numerous collectible coins, including dollar coins from different years and mints, such as the 1899 Philadelphia Mint dollar. A roll typically contains 20 coins and is often used for standardized packaging of collectible coins, enhancing their desirability among collectors and investors alike.