I live right down the road from Coopers. It's my morning coffee stop and I usually hit it up for lunch on Saturday when I am piddling around in the yard.
They have a hot bar for lunch now. It's usually fried chicken, fried quail, pileau and some types of vegetables. I can't tell you it's an emotional experience, but the fried quail and rutabagas I had last Saturday were good to me.
I've been driving from salters to concord, nc twice a week since last august for a project up there and have come across a couple of places that I haven't really stopped at because nothings really open at 5AM when I go through Bishopville and Bethune. There's a gas station on the road between those two towns though. I've stopped for a bologna and egg sandwich a few times. Place isn't much to look at, but like Cooper's, it's a hardware store, gas station, auto parts store with a meat counter.
The Watermelon Patch in Pageland has good breakfast and clean bathrooms. https://thewatermelonpatchpageland.com/menu/ - I'm not sure why anyone would go to Pageland, except to go through Pageland.
On 601 from Monroe NC to Concord NC there's a shipping container converted into a walk up burger joint that has a good burger. Place is called Hot Mess. https://hotmessburgers.com/
Last place isn't really what I'd call a Culinary Landmark, but the place in McCleod farms in McBee has a restaurant.