Walgreens is a chain drug store with 8 locations in Oakland. They sell over the counter and prescription drugs, packaged foods with a long shelf life, knick-knacks, light art and office supplies, plastic trinkets. Odds and ends. It's the kind of place you go when you have a mission. A purpose. An objective. Otherwise the hum of the fluorescent lights and drab shelves will lull you into vegetative and delirious state.
You can buy clipper cards at any Walgreens location in the bay area.
Walgreens now has a healthy food line of pre-made foods, so if you're desperate, you can go there.