One strategy I employed while hiking the PCT was to drift a box with specialty items that I knew I would never be able to find in a grocery store, things I had to mail order special, freeze-dried fruit, Nido full-fat powdered milk, other things I can't remember.
Another strategy was to never mail anything that could be purchased at a gas station market!!!
So what did I get at the grocery store?
– Noodles, specifically orzo (denser) and elbow macaroni (cheapest). Regular pasta cooks just fine if you remove from heat and let it stand in the pot wrapped in a hat for 15 minutes to two hours. No need to seek out special faster-cooking pastas.
– Sauce packets. There's practically half an aisle devoted to special sauce packets. I favored the Alfredo Cheese, Four Cheese and there was one that was Parmesan cheese and tomato that was pretty good. Add that to my noodles. Costs more than mac-and-cheese but has a gourmet flair. There are other flavors like chili, Mexican, gravy etc.
– Tuna, chicken and Spam in foil packets.
– Dry salamis, hard cheeses.
– Breakfast cereal, nuts from the baking aisle rather than the nuts aisle, cookies and crackers.
– Dried black bean soup can be reconstituted into dried "refried" beans by simply adding less water.
– Jerky, nuts, dried fruit, candy, sports energy bars and stuff like that, the usual suspects.
– Poptarts, other breakfast pastries, oatmeal bars etc. Honestly, I think that fig newtons are healthier.