Staples and Produce
The FDA requires the same standards of production, ingredients and storage for generic versions of staples like flour, sugar, salt and spices. Obscure details of production aside, it's almost impossible to find a difference beyond labeling for these products.
Salt, for example, is a simple chemical compound. Beyond the usual added iodine, there isn't much variation from the recipe between store brand, generic or name brand. However, the differences in price can be astounding: An ounce of name-brand oregano, for example, can sell for almost four times as much as the generic, and the only difference is the name on the label.
Likewise, produce and precut salad mix are two more categories where corporate origin has little to do with quality or freshness. In fact, it's a good idea to ignore those little brand-name stickers altogether and go with your eyes and nose. Otherwise, you'll end up paying for the sticker, with no difference in quality at all.