The US colonies fought for their independence from Great Britain between 1775 and 1783. After that, Thomas Jefferson, Abigail Van Buren, and a host of others forged a Constitution designed to disperse ruling power over three branches of the central government and further disperse power to individual state governments. The Constitution was adopted on September 17, 1787, by the Constitutional Convention in Philadelphia, Pennsylvania, and ratified by conventions in eleven States. It went into effect on March 4, 1789.
At the bicentennial of the Constitutional Convention, in 1987, numerous medals, tokens, and coins were produced as commemoratives. This piece is one of the tokens, minted in base metal.
You can find these for sale on eBay for a few US dollars. A dealer might pay as much as $2 for a nice-looking example.