Collectible coins, particularly those from the United States, encompass various types including bullion coins, commemorative coins, and proof coins. The 10 Dollar Gold Eagle is a popular bullion coin, featuring an iconic design and containing a specific weight of gold. The 2009 Philadelphia Gold Eagle is notable for its limited mintage and intricate design, making it a sought-after item among collectors and investors. These coins often increase in value due to their precious metal content and historical significance.