RICHMOND, Va., Aug. 12 -- The U.S. Postal Service issued the following news release: Considered one of the greatest American painters of the 19th century, Winslow Homer is being honored today on a U.S. commemorative postage stamp. The new 44-cent stamp was dedicated here at the American Philatelic Society StampShow 2010, the largest annual postage stamp show held in the United States. It is the ninth issuance in the American Treasures series and features Boys in a Pasture, an 1874 oil-on-c  more