There is some shale near the creek beds in the southern side of Fayetteville. It ranges from the I-540 Overpass near Martin Luther King, Jr (formerly 6th street) to Cato Springs Rd. on the south and 71-B on the east. Some flat concretions up to 12 inches and ammonites of various small sizes have been found, some with pyrite. I think some of the large cephalapods were found in this area.

Attaching a map: Location #1 is a wash exposure of shale with siderite nodules (that have the ammonites in them) behind the Travelodge dumpster.  Location #2 is a hillside exposure of shale with more siderite nodules just before reaching a church near the end of the access road going south from 6th street/MLK blvd. 

Location #3 is straight across from the Red Roof Inn in the ditch.  There is a black shale exposure there as well, and you'll be looking for pea-sized ammonites that are pyritized.  Location #4 is in a creek near the south west corner parking lot of the Crown Pointe apartments.  There are septarian concretions with ammonites, large grey septarian concretions that look like turtles (I cleaned out the surface ones), and Jacob found a 6-8 inch cephalopod in great condition there last weekend.