In the 60s in hs, I worked part time at a Sinclair station in Cleveland. They had sales promotions like a free box of laundry detergent or sometimes free dish towels. Also I remember some kind of off brand soda pop as a giveaway item for a fill-up.
Top kek for us as kids (long before we knew what "kek" meant) was a plastic container of "Tub Candy", which we got at the various Stuckey's restaurants/travel stops on the family 's route to visit my Dad's folks out of state. Tub Candy was very sticky peanut brittle that had probably sat in the sun way too long, but we clamored "MORE TUB CANDY! MORE TUB CANDY!" every time.