Stamp collecting began for me as a very young boy with the purple 3¢ Jefferson. It was a scheme of my Mom’s to keep me occupied with ‘busy work.’ She gave me envelopes from the day’s mail (where Jefferson reigned), safety scissors, paste, and cardboard. Cutting Mr. 
Jefferson from countless envelopes, slicing away perforations with abandon, pasting rows and rows of that bust on cardboard was stamp collecting to me. What a marvelous time I had!
The 3¢ Jefferson was part of the USPOD’s Presidential Issue definitive series (called ‘Prexies’ by many collectors) issued in 1938 that featured all 29 U.S. Presidents through Coolidge. The set also included two fractional-cent denominations with busts of Franklin and Martha 
Washington, and another featuring of the White House. Face values ranged from ½¢ to $5, so every possible postal usage was covered.
A national competition was held to
determine the design of the series, and the entry by Elaine Rawlinson, a New York artist, was selected. Her 1¢ rendering was based on a bust of Washington (right) by sculptor Jean-Antoine Houdon. The 3¢ 
Jefferson was also based on a bust by Houdon, with the die portrait engraved by Carl T. Arlt and the lettering by James T. Vail.
To my eyes now, the overall look of these stamps is bland, but as a child these disembodied heads and color varieties were mesmerizing. 1¢ and 2¢ versions also appeared on our mail, and very occasionally higher denominations. I was ‘happy as a clam’ with this busy work involving little colored heads.
The 3¢ Jefferson was the workhorse of first class mail from 1938 to 1954, when the 3¢ value from the 6th Bureau Issue was introduced. Will we ever see another stamp issued in a quantity of 138,000,000,000?
For much more info about The Prexies, I suggest a book with that title authored by Roland E. Rustad.
We all know about the Inverted Jenny…Right? But a few days ago I learned that the Jenny airplane really isn’t inverted!