About 7 miles north of the Badlands Visitor Center is the Badlands Ranch Store. For a nominal fee, you can purchase a coozie emblazoned with their logo and full of unsalted peanuts in a shell.
After you have made your purchase, you can go to the other end of the parking lot where there is a small prairie dog town. It is full of fat, well-fed and fairly friendly prairie dogs. I have to say this was incredible feeding these guys!