This past Thursday, as it has done every year since 1948 (when it was designated the "official ceremonial unit" of the United States Army), the 3rd U.S. Infantry Regiment (The Old Guard) placed flags on over a quarter-million tombstones at Arlington National Cemetery. It was one of the increasingly few observances of Memorial Day which remains true to the holiday's original intent.
Once known as Decoration Day, the holiday's origins remain a source of some controversy. What we do know is that celebrations of the holiday have changed considerably over the past 140+ years.
Although not a lot of books have been published about this holiday, a fair number of pamphlets survive from the days when the original intent of the holiday was more widely and officially celebrated (the pamphlet depicted above is from ReRead Books in Little Rock, Arkansas). Robert Schauffler's Memorial day: (Decoration day) its celebration, spirit, and significance as related in prose and verse, with a non-sectional anthology of the Civil War (1911) remains probably the most comprehensive look at this holiday from the era when it was widely celebrated as originally envisioned. (Original copies of this book are quite scarce, but it remains available in the marketplace as a print-on-demand title.)
The most comprehensive modern examination of the holiday appears to be History of Memorial Day: Unity, Discord, and the Pursuit of Happiness (Richard Harmon & Thomas Curran, 2002). Part of the series American University Studies, the title surveys how celebrations of the holiday evolved from 1869 to 1993.
In the modern era, more children's books about this holiday appear to have been published than books aimed at adults. Examples include Christin Ditchfield's Memorial Day, as well as Robin Nelson's, Mir Ansary's and Trudi Trueit's books of the same title. (The question of whether the holiday should be called Memorial Day or Decoration Day is at the heart of David Brown's self-published fiction title The Decoration/Memorial Day War....)