Private label
Every major grocery chain offers “private label” items, with their own brand packaged over goods produced by other unnamed companies.
You can peek into what companies produce private label items via recalls. Sargento recalls, and “coincidentally” Costco, Trader Joe's, and Walmart also recall at the same time.
Private labeling constitutes a form of backward integration. Generally, major grocery chains take from producers and give to consumers, pocketing some for themselves, of course. As a producer, can you really afford to not appear on Walmart shelves?
Some small producers, though, claim major grocers steal their product ideas under the guise of private labeling. Every intermediary (grocery stores intermediate between grocery producers and consumers) must contend with how much they give and take from each side, and how much they keep for themselves.