An album. Go find some old pictures from over the years (they must have many in an old box or stashed away somewhere) put together an album with maybe parts of some old letters or something. You don't have to cut up the letters, photocopy them and then cut out a sentence or two? Or a paragraph? A memento could be put in the album too. I promise you, it will make them smile and talk and remember and yes, maybe a tear or two but that's OK too.