On a tight food budget? Here are seven inexpensive and nutritious items you should consider adding to your grocery list.Trying to live on a food budget of about $4 per day can be quite a challenge. People quickly discover this when they take the Food Stamp Challenge and try to learn what it's like to be poor for a week. The challenge mirrors what someone can get through the Supplemental Nutrition Assistance Program, or SNAP, the federal program that helps low-income people buy groceries. One in seven Americans receive the benefits, which were significantly reduced by Congress in November. To...