What are some "AMERICAN THINGS" that I can bring to Spain with me?

Your best gifts include things that are personal, and things that are hand-made. Things that you find at craft fairs and at those shops that are in some malls where people sell their hand made things. Things that represent your home town, school shirts/hats from your town, not big teams they can get there. Don't bring Dallas Cowboys things, but a home-town soccer team or your high school or college shirts (again, not Yale or big-name schools, but small ones, they haven't access to online. Actually, they aren't likely to know UConn.) make good gifts. food products they can't get...again, locally made things, they can get Nestlé (actually a European company, and they have their own plant in Barcelona), but the little shop around the corner where they make their own by hand, that, they can't get.