The Two-dollar Prexie
The 29th President of the United States was Warren G. Harding. He is pictured on the two-dollar stamp in the Prexie series, from a likeness taken from a medal produced by the U.S. Mint.
The two-dollar Prexie is the second value produced in two colors. It was issued in sheet format only. Its first day of issue was September 29, 1938, and only 13,571,578 were issued through 1955.
There were no specific two dollar rates during the Prexie period. Solo covers are scarce, and usually involve parcel shipment or foreign airmail. There is no point in trying to enumerate possible combinations, so I will just list those I can illustrate. The list will not be long.