Johnny Appleseed, born John Chapman, was an American pioneer nurseryman who introduced apple trees to large parts of Ohio, Indiana, and Illinois. He became an American legend while still alive, largely because of his kind and generous ways, his great leadership in conservation, and the symbolic importance he attributed to apples.
Johnny Appleseed day is celebrated on March 11 and again on September 26. According to legend, ink it is because Johnny Appleseed may have died March 11th (although Wikipedia lists March 18, 1845) and his date of birth was on September 26th. No one is exactly sure who started the observance but it is celebrated by many across the nation.
Photo by ollesvensson
For more information on Johnny Appleseed, you can read: