This fare is available for travel on Tuesday, Wednesday, and Saturdays, starting on August 14 through September 29, 2018. This fare books into American's Basic Economy fare class which restricts you to a small carry-on like a purse or backpack. If you think you'll need access to that overhead bin and want to pack a larger sized bag to bring onboard, the Main Cabin fare is selling for $131 round-trip.
Searching on the American website, I could find seats departing DFW on Wednesday, September 12, and returning from ATL on Saturday, September 15, 2018.
Need a room in Atlanta? No worries, there's a long list of available hotels for the mentioned dates above on Hotelwatchdog.