F-Cards represent issues from various food companies. These are mostly later issues that came out after companies discovered the fascination of collectors with candy and tobacco products.
Several issues are not traditional cards, either. The Wheaties Panels, for example, are actually the oversized pictures on old Wheaties boxes. Despite that, many of these products have become collectible over the years.
F-Cards come in all shapes and sizes. One unique issue is the 1938 Dixie Lids set. These were literally lids off of the top of ice cream products that featured a variety of athletes, including football players.