Best deals for grocery shopping ?

Hi everyone, I'm planning my stay in LA, and I was looking at the various options for grocery shopping. I live in France and I was already surprised by the price of the products but anyway. What is the best value ? What should I know before coming to a grocery store? And big question: you don't sell drinks by the can? lol. I would be in the rosemead area. Thanks y’all ! EDIT : for the term « stay »