It is a musical instrument called an Aoline or Aura, manufactured from about 1821 to 1835. I dug one many years ago at a plantation which had a CS campsite near Charleston SC. It seems to have very thin sheet copperbrass reeds attached by tiny iron rivets to a body made of high tin-content pewter. The body of mine has scaled pretty badly over the years since it was dug.
Note that the reeds at right are on the body's "topside" and the reeds on the left are on the "underside." That allows the instrument to be played on both the inhale breath and exhale of the user.
The photo below contains lots of information about your find. Click on the photo once and then a second time to super-enlarge it. That photo was originally posted here in the What-Is-It? forum by our fellow relic-ID helper Creskol.
