No April Fooling here today. I'm either not creative enough or don't wish to fool you, but I didn't want to ignore the day either. So we'll take a folkloric approach to it.
April Fools' Day or All Fools' Day is a day celebrated in various countries on April 1. The day is marked by the commission of hoaxes and other practical jokes of varying sophistication on friends, family members, enemies, and neighbors, or sending them on a fool's errand, the aim of which is to embarrass the gullible. Traditionally, in some countries, such as the UK, Australia, and South Africa the jokes only last until noon, and someone who plays a trick after noon is called an "April Fool". Elsewhere, such as in France, Ireland, Italy, South Korea, Japan, Russia, The Netherlands, Brazil, Canada, and the U.S., the jokes last all day. The earliest recorded association between April 1 and foolishness can be found in Chaucer's Canterbury Tales (1392). Many writers suggest that the restoration of January 1 as New Year's Day in the 16th century was responsible for the creation of the holiday, but this theory does not explain earlier references.
Ancient cultures, including those of the Romans and Hindus, celebrated New Year's Day on or around April 1. It closely follows the vernal equinox (March 20th or March 21st.) In medieval times, much of Europe celebrated March 25, the Feast of Annunciation, as the beginning of the new year.
In 1582, Pope Gregory XIII ordered a new calendar (the Gregorian Calendar) to replace the old Julian Calendar. The new calendar called for New Year's Day to be celebrated Jan. 1. That year, France adopted the reformed calendar and shifted New Year's day to Jan. 1. According to a popular explanation, many people either refused to accept the new date, or did not learn about it, and continued to celebrate New Year's Day on April 1. Other people began to make fun of these traditionalists, sending them on "fool's errands" or trying to trick them into believing something false. Eventually, the practice spread throughout Europe.
There are at least two difficulties with this explanation. The first is that it doesn't fully account for the spread of April Fools' Day to other European countries. The Gregorian calendar was not adopted by England until 1752, for example, but April Fools' Day was already well established there by that point. The second is that we have no direct historical evidence for this explanation, only conjecture, and that conjecture appears to have been made more recently.
It is worth noting that many different cultures have had days of foolishness around the start of April, give or take a couple of weeks. The Romans had a festival named Hilaria on March 25, rejoicing in the resurrection of Attis. The Hindu calendar has Holi, and the Jewish calendar has Purim. Perhaps there's something about the time of year, with its turn from winter to spring, that lends itself to lighthearted celebrations.
Another site that explains well for the elementary and middle school set: April Fool's Day although it doesn't offer alternate possibilities, it's well-written with what it offers including some extras about "kick me" signs and the like.
And for your reading humor, The Top 100 April Fool's Day Hoaxes of All Time. (I have to agree with the masses that the spaghetti harvest is one of the best of all time.)