Collectible coins encompass various categories, with "So-Called Dollars" being a notable type. These coins generally refer to medals or tokens that resemble U.S. dollar coins but were not produced as legal tender. The Hibler and Kappen reference indicates a classification from a specific catalog, which documents these pieces. An example is the 1826 So-Called Dollar, recognized for its historical significance and collectible appeal, often attracting numismatic interest for its rarity and unique designs.