Sometimes even pictures, a small toy, and your favorite candy does the trick. You can always have someone send a care package with any other goodies you suddenly realize you absolutely need. A good tip is to have someone fill a $15 international 4lb flat rate USPS box with trinkets from home. You have to remember most American items tend to run pretty pricey compared to being purchased in America. A good example is peanut butter, which is pretty pricey everywhere else in the world. If you cannot live with out it, take a little bit to cheer you up when homesick.