Like others who have posted, I use coupons mostly for non-food items, in my case, sponges, foil, shampoo, toothbrushes, cleansers.
But I do use a few coupons for food when I find them. I love Ragu spaghetti sauce, so I use those. I buy some canned soup (although Campbell's has gotten so poor in quality over the years, I don't get much of it), so I use the soup coupons. Sometimes I'll use the ones for spices (Spice Island, McCormick), though I prefer buying spices from bulk sellers.
You're right, it's mostly the processed foods that have coupons. Sometimes I use coupons for junk foods such as cookies or ice cream.