First U.S. Forever Stamp Issued
On April 12, 2007, the USPS issued its first Forever stamp, which featured a patriotic image of the Liberty Bell.
The USPS has issued non-denominated postage in the past. In 1975, they were unsure when and how much the postage might increase, so they issued that year’s Christmas stamps without denominations. That saved them from having to print hundreds of millions of stamps with a new denomination. The rate increase, from 10¢ to 13¢, occurred just after Christmas.