For what it’s worth, a LOT of farmers’ markets these days have many things other than produce. They often have crafts, wine, liquor (if the state allows that to be sold at such a place; not all do), and so on. I wouldn’t go out of my way to go to one, but if you’re somewhere that has one, it can be fun to spend a half hour browsing.
It looks like you’re going into Pennsylvania for part of the trip - what part? (not clear from the map). Philadelphia has lots of history and interesting stuff to see, though to my mind it doesn’t require more than a day or two. Going a little west of there will take you to the Harrisburg / Hershey / Lancaster area, where you’ll see the Hershey Chocolate factory (no tours of the actual factory anymore, but there’s a free indoor ride / exhibit), and may even encounter some Amish people. One of the most amusing “cognitive dissonance” moments I’ve ever had was in Strasbourg, PA, watching a gentleman drive his buggy through a bank’s drive-through lane.