I buy the giant tubs of organic spring mix and spinach for $3.98, which is half of what the supermarkets charge. I share it with my son so it doesn't have a chance to go bad and we buy it weekly.
I also buy their portabella mushrooms. They cost 3.99 for a 4 pack and they are always the hardest mushrooms in town. Perfect
We buy frozen fruit and vegetables from Sams.
They do have cheap canned/jarred products but the vast majority of them are highly processed. We don't even go down those aisles anymore. It's amazing - and sad - how much junk food they sell.