As of 2014, the Mystic Stamp Company states that the 1968 Thomas Jefferson green 1-cent stamp is valued at about 20 cents in mint condition and 15 cents if used. Due to its relatively young age, it is still extremely common and not highly sought by collectors.
The stamp is part of the "Prominent Americans Series" released from 1968 to 1981 with the intent of recognizing 25 individuals who played an important role in U.S. history. The Jefferson stamp bears the lowest face value of the group. The first issue of the series was the 1965 Abraham Lincoln 4-cent stamp, and the series concluded with the 1981 George Washington 5-cent issue.