Your can stretch your grocery bill when you stretch your food. I do it all of the time, and it helps me keep our grocery bill less than $100 a week for a family of five. Now that is great grocery savings.
So many meal items can be stretched without compromising health or flavor. For example, I frequently stretch out ground meat with bread crumbs, oatmeal, TVP or even wheat germ (if I get it on sale). Meat is expensive, so it is one good area to stretch. This works for pretty much anything that uses ground beef, hamburger, chicken, or turkey, such as casseroles, burgers, and meatloaf. Beans are another cheap ingredient that can stretch or substitute for meat. Beans are very nutritious, too.
While my kids don’t like the taste of powdered milk straight up, I still use it to stretch meals. I add the powdered milk in my bread, pancakes and baked goods. There is no taste difference when using it these recipes, but there is quite a bit of cost difference. You can also try to stretch out your actual drinking milk with powdered milk. One word of caution, the taste of powdered milk is apparent when you use it to make something that is heavily milk based, such as pudding or ice cream!
Stretch out your vegetables by adding them to dishes or preparing them in a way that makes them seem to multiply. For example, mashed potatoes tend to go a lot farther than serving everyone an individual potato. Using the broccoli stems in a casserole or side dish rather than just serving the broccoli heads by themselves will allow you to feed more people on less.
Other places to stretch include your dishwasher. I usually buy dishwashing detergent at the grocery store, so this counts for me as grocery savings. The dishwashing detergent can be stretched with regular and less expensive borax and baking soda.