Collectible coins, including U.S. coins, often hold value due to their rarity, historical significance, and condition. The 2001 coins minted in Philadelphia, such as the dollar coins, may be collected for their design, mintage figures, or as part of a larger series. A roll typically contains 25 coins and can be sought after by numismatists and investors alike, particularly if the coins are in uncirculated condition or have unique attributes.