By Brandy McDonnellPIGGOTT, ARKANSAS — Post Office lobby artwork painted in the 1930s and 1940s, including an Anadarko mural created by one of the Kiowa Six artists, was celebrated today with the issuance of the Post Office Murals Forever stamps.The U.S. Postal Service dedicated the stamps today during a first-day-of-issue ceremony at the Piggott Main Post Office in Piggott, Arkansas, according to a news release.“Scores of wonderful murals illuminate Post Office lobbies across the nation and these stamps help celebrate them as American treasures,” said Pat Mendonca, U.S.