The observance began in 1872, when Nebraska settlers and homesteaders were urged to plant trees on the largely treeless plains.Mother's Day celebrates mothers every second Sunday of May. President Woodrow Wilson, who issued a proclamation in 1914, asked Americans to give a public expression of reverence to mothers on this day. Carnations have come to represent Mother's Day, following President William McKinley's habit of always wearing a white carnation, his mother's favorite flower.Memorial Day is a federal holiday observed the last Monday of May. It originally honored the people killed in the American Civil War, but has become a day on which the American dead of all wars, and the dead generally, are remembered in special programs held in cemeteries, churches, and other public meeting places. The flying of the American flag is widespread.Flag Day, celebrated June 14, has been a presidentially proclaimed observance since 1916. Although Flag Day is not a federal holiday, Americans are encouraged to display the flag outside their homes and businesses on this day to honor the history and heritage the American flag represents.Father's Day celebrates fathers every third Sunday of June. Father's Day began in 1909 in Spokane, Washington, when a daughter requested a special day to honor her father, a Civil War veteran who raised his children after his wife died. The first presidential proclamation honoring fathers was issued in 1966 by President Lyndon Johnson.Independence Day is July 4. This federal holiday honors the nation's birthday - the adoption of the Declaration of Independence on July 4, 1776. It is a day of picnics and patriotic parades, a night of concerts and fireworks. The flying of the American flag is widespread.Labor Day is the first Monday of September. This federal holiday honors the nation's working people, typically with parades. For most Americans it marks the end of the summer vacation season and the start of the school year.Columbus Day is a federal holiday celebrated on the second Monday in October. The day commemorates October 12, 1492, when Italian navigator Christopher Columbus landed in the New World. The holiday was first proclaimed in 1937 by President Franklin D. Roosevelt.Halloween is celebrated on October 31. On Halloween, American children dress up in funny or scary costumes and go "trick or treating" by knocking on doors in their neighborhood. The neighbors are expected to respond by giving them small gifts of candy or money.Veterans Day is celebrated on November 11. Originally called Armistice Day, this federal holiday was established to honor Americans who had served in World War I, but it now honors veterans of all wars in which the U.S. has fought. Veterans' organizations hold parades, and the president places a wreath on the Tomb of the Unknowns at Arlington National Cemetery in Virginia.Thanksgiving Day is a federal holiday celebrated on the fourth Thursday in November. The holiday began in 1621, when Puritans, who had just enjoyed a bountiful harvest, showed their gratitude to the Native Americans for their help by hosting a feast to give thanks. The Thanksgiving feast became a national tradition and almost always