For your personal edification, here is a little history of how the day came to be, from www.usflag.org. My only disclaimer about this post is my fear that Flag Day, as opposed to July 4th or Memorial Day, fetishizes the flag rather than commemorates what it represents.
The Fourth of July was traditionally celebrated as America's birthday, but the idea of an annual day specifically celebrating the Flag is believed to have first originated in 1885. BJ Cigrand, a schoolteacher, arranged for the pupils in the Fredonia, Wisconsin Public School, District 6, to observe June 14 (the 108th anniversary of the official adoption of The Stars and Stripes) as 'Flag Birthday'. In numerous magazines and newspaper articles and public addresses over the following years, Cigrand continued to enthusiastically advocate the observance of June 14 as 'Flag Birthday', or 'Flag Day'.
On June 14, 1889, George Balch, a kindergarten teacher in New York City, planned appropriate ceremonies for the children of his school, and his idea of observing Flag Day was later adopted by the State Board of Education of New York. On June 14, 1891, the Betsy Ross House in Philadelphia held a Flag Day celebration, and on June 14 of the following year, the New York Society of the Sons of the Revolution, celebrated Flag Day.
Following the suggestion of Colonel J Granville Leach (at the time historian of the Pennsylvania Society of the Sons of the Revolution), the Pennsylvania Society of Colonial Dames of America on April 25, 1893 adopted a resolution requesting the mayor of Philadelphia and all others in authority and all private citizens to display the Flag on June 14th. Leach went on to recommend that thereafter the day be known as 'Flag Day', and on that day, school children be assembled for appropriate exercises, with each child being given a small Flag...
Inspired by...three decades of state and local celebrations, Flag Day - the anniversary of the Flag Resolution of 1777 - was officially established by the Proclamation of President Woodrow Wilson on May 30th, 1916. While Flag Day was celebrated in various communities for years after Wilson's proclamation, it was not until August 3rd, 1949, that President Truman signed an Act of Congress designating June 14th of each year as National Flag Day.