I have been rescuing food for quite some time now and have gotten pretty familiar with which stores are the best for finding an abundance of certain kinds of foods. Dumpster diving has saved me a tremendous amount of money I'd otherwise spend on groceries, and has allowed me to feel more ethically secure in consuming outside a wasteful capitalist system.
I usually have no problem finding breads and various other baked goods (croissants, doughnuts, bagels, muffins, etc.), packaged sandwiches (starbucks, au bon pain, trader joes, hale and hearty, etc), pizza, and vegetables. Fruits are fairly common as well -- especially berries and bananas -- though they very well may be bruised (good for anyone interested in making smoothies!) Nonperishables like cereal and canned foods are rare, but not impossible to find. One lucky night I found 4 big packages of various dry beans!
I want to offer one night of my dumpster diving services -- yielding about 3-4 bags of food -- to anyone interested. While I cannot guarantee getting any specific items, I can search for food based on certain dietary preferences (vegetarian, vegan, gluten-free), and can definitely keep in mind any general food preferences when searching for food.