Easter is a moveable feast, meaning it changes depending on a few things. The council of Nicea 325 determined that it would occur after the full moon following the vernal equinox on the next occurring Sunday, unless this happened to interfere with Passover, in which case it should be the Sunday after that. Got it? It can occur anytime between March 22 and April 25.
Sources: history.com
The tradition of eating ham most likely came from the slaughter of an animal before fall and then preserved in salt over the winter, sometimes buried near the sea. 67 percent of Americans serve ham at their Easter dinners, according to pork.com, and this typically breaks any meat fast that is undertaken during Lent.