The Ozarks is a beautiful little region that covers northern Arkansas, southern Missouri, and a tiny bit of Oklahoma. Hills, rivers, and limestone caves cover the area. It's a great place for fishing and, unfortunately, tornadoes.
Blanchard Springs Caverns has three levels of cave exploration, depending on your agility. Also very nice surroundings outside.
Devil's Den State Park also offers caves, plus interesting formations.
Besides tornadoes, the region is prone to occasional flooding, and also horrendous ice storms.
The strange, non-edible citrus fruit called the Osage orange also grows in the Ozarks. It's said to repel insects and deodorize your refrigerator. Here are some from the Fayetteville/Prairie Grove area.