FFO Name: Crown
"Crown that shimmers mysteriously."
You find the Crown in the Marsh Cave. Taking it to the lone king at the Northwest Castle will result in getting you the Crystal.
Like the Lute, the Crown kept it's name from the Japanese version. If you don't know what I crown is, what's wrong with you? It's a hat (usually made of gold and covered in pretty things) that kings wear. (Cool note, the first thing listed for crown in my dictionary is "GARLAND".)