Keep in mind that my list is probably going to look different than others. I buy a couple of convenience foods (ketchup, boxed cereal, etc.) but most everything I purchase are staples because I do all my cooking from scratch. I started doing that about 15 years ago because I have a daughter with severe, multiple food allergies and I didn't want to take a chance that she would have an anaphylactic reaction. Then I found that it was much cheaper to cook this way.
I keep a certain amount of each item in my pantry and when I go shopping, I restock whatever is below the normal amount. So if I normally would have 10 cans of diced tomatoes and I use up 5, when I go shopping I purchase 5 more.
Here is my list:
Meats-I tend to purchase the same kinds of meat but I will get it when it's on sale. So if I go to the store and chicken breast is on sale, I will stock up on that. The next time ground beef or pork may be on sale, so I'll stock up with those. Eventually, I have a good stock of meat in my freezer to choose from.
Beef - this is almost never purchased anymore because of the cost. Prices are crazy!
Fish when there is a good sale
Tomato sauce - I can my own
Salsa - I will make my own in the summer time
Spaghetti Sauce - I keep about 2 jars on hand for when I make pizza so I can just put sauce on it without having to make it from scratch. The rest of the time I make my own.
Sweetened condensed milk
Cherry pie filling
Vinegar - balsamic, red wine vinegar, rice vinegar, white, and apple cider
Grains & dried legumes
Unbleached white flour
Whole wheat flour
Oats - old-fashioned rolled oats, quick, and steel cut
Rice - brown, wild, white
Sugar - white, brown, confectioner's sugar
Spices - too many to list
The rest of the frozen veggies are from our garden
Ice cream - the one splurge we have though I have made it in the past and it's much better than store bought
Fresh Fruit & Veggies-I buy in season
I'm sure I'm missing some things but this gives you a general idea. Anyway, that's my frugal contribution for the week. You can head over to Rebecca's blog for more ideas.