The 6-cent Edgar Lee Masters stamp, part of the American Poet series, was first placed on sale at Petersburg, Illinois, on August 22, 1970. Edgar Lee Masters (1869-1950), a renowned American poet and writer, was born in Garnett, Kansas, and raised in Illinois. Masters' most notable work was the "Spoon River Anthology." The stamp was designed by Fred Otnes and was issued in panes of fifty, with an initial printing of 125 million.
Postal Bulletin (July 23, 1970).
Primeau, Ronald. "Edgar Lee Masters' Life and Career." http://www.english.uiuc.edu/maps/poets/m_r/masters/life.htm (Accessed 24 April 2008)