So-Called Dollars are a category of collectable coins and medals that commemorate significant events or people, often in a size similar to a standard dollar coin. The term originated from issues around the late 19th century, particularly around the 1899 piece that recognizes the Trans-Mississippi and International Exposition. These items are not official currency but are sought after by collectors for their historical significance and artistic design. The 1899 So-Called Dollar is notable for its elaborate engravings and connection to American history.