Jew's Harps/Trumps are different than Mouth Bows in that M.B.s are really bows (like, "bow-&-arrow"), that, as the Jew's Harp, use your body cavity as resonator.

The U.S. version I've often heard referred to as a "Chickasaw Mouthbow". These are strummed with a feather quill or some such plectrum. The African mouthbows (Central and Southern) I know of are either plucked, or percussed with a small stick.