I have a family of four (two adults, a 4 and a 6 y/o) and live in a similar middle-America MCOL city. I spend about $500/month on groceries, which I consider one of our least frugal habits.
For example, here are the kinds of things we buy:
-Meat/Dairy - local, grass-fed non-organic options from the natural foods co-op (the brand we buy isn't organic because they do give their animals antibiotics on an as-needed basis) This is the choice we make for animal welfare reasons, so we almost never buy conventional animal products. We pay for this, but consider it well worth it.
-Produce - Primarily in-season or on-sale options from Target, Whole Foods, local co-op or farmer's market
-Staples - Mostly from Costco or Target, occasionally Trader Joe's; dried beans, pasta, peanut butter, nuts, canned tomatoes, etc. Also from local ethnic shops for things like olive oil, rice, masa de tamal, masarepa, etc.
-Spices, tea and coffee - in bulk from the co-op, or occasionally from the local ethnic shop (for stuff like black peppercorns that we'll go through fast, or the imported paprika that my husband insists on)
Here's the kinds of things we DON'T usually buy:
-Individually packaged snacks, or really most snacks (cookies, chips, crackers, fruit sauce pouches, etc.). I'll bake cookies or brownies if we want them, or we eat nuts or dried fruits.
-Soda or other beverages. We almost never have juice; we eat whole fruits instead. We'll buy beer or wine occasionally but also brew our own.
-Prepared foods like boxed dinners, mac and cheese, frozen pizzas or other frozen meals, etc.
-Stock. We save meat carcasses in the freezer and make our own stock.
I'll grant that a lot of the reason people buy these kinds of things is the convenience. My husband loves to cook, it's relaxing for him, so that's not a compelling reason for him. I also think that there are plenty of from-scratch options that take the same amount of time as the boxes. Like mac and cheese: pasta takes the same amount of time to boil whether it comes with a packet of powdered cheese or not. While the pasta is boiling, you can grate the cheese and mix up the sauce and be ready to mix it all together when the pasta is done.
Here's what we're eating this week. This is heavy on soups and soft foods because my 6 y/o just had his tonsils out.
-Butternut squash soup with fresh sage and sausage, made in the Instant Pot. (We grow sage in our garden. Ground pork was on sale but sausage wasn't, so I bought the pork and spent 5 minutes to mix up sausage from an internet recipe with spices I had on hand. Stock was homemade. Squash was an impulse purchase because it was the first squash of the season, local and organic from the co-op.)
-"Morning flatbread" (improvised homemade version of Ozery's morning rounds) with peanut butter (we buy the large jars from Target; Costco would be cheaper but I'm a loyal Skippy Natural Chunky eater)
-Homemade mac and cheese (I found a 20lb box of elbow macaroni at Costco this past weekend. Local mozzarella, cheddar, yogurt and egg from the co-op. Spices we had on hand.)
-Black beans, arepas and rice with roasted sweet potatoes and fried plantains (Black beans made in the instant pot with homemade stock and chunks of pork we bought on sale and kept in the freezer. Arepas from scratch, takes maybe 20 minute, from a 5lb bag of masarepa bought at the local hispanic market. Also got the plantains at the same market.)
-Scrambled eggs with toasted homemade bread.
-French onion soup (homemade stock, topped with homemade bread and gruyere. The gruyere was a total splurge.)
-Chicken tikka masala (another Instant pot recipe, local chicken, spices we had on-hand. TJ's shelf-stable heavy cream is a lifesaver.) Homemade garlic naan (takes only 20 minutes of actual work)
-Vegetable stir fry (Using up bits of various vegetables in the fridge before they go bad, sauces we had on hand, served over rice noodles we got a large box at the local Asian market.)