There was a pair of rest areas on on opposite sides of the Baltimore-Washington Parkway, or MD-295, just north of where the Arundel Mills Blvd. interchange is now, partly sharing the same footprint in fact. These weren't really "rest areas" as we know it, though. All the areas had was a strip of pavement parallel with the highway, and a string of payphones on the left, close enough to call from your car. I think the signage on the BW Parkway said "Pay Phone Rest Area" or something to that effect. Rather unusual concept, I must say.
These rest areas must have closed some 15 years ago to make way for the Arundel Mills Blvd. exit. No big loss, it seems, since cell phones were starting to become commonplace by then. Since the spaces were re-landscaped for the ramps, and the rest areas were quite narrow to begin with, little if any evidence of them appears to remain.