I was going to mention this species being adapted for egg-eating as well. In the Trans-Pecos rat snake book by Dusty Rhoads, it does say that they eat eggs as well (saying they have taken them in captivity, I think?). I would be nervous feeding a larger egg (like a chicken egg) to anything smaller than an adult Eastern Indigo snake lol, but I do know some wild rat snakes eat chicken eggs.
I was surprised to see quail eggs at my Publix, but I think it is a seasonal offering (their entire inventory changes for the snowbird residents and they carry more esoteric food then).