Johann Sebastian Tishman
Earliest known American Baroque composer, according to the liner notes of the classical music parody album Baroque Americana by "The Concertgebluff Authaus Orchestra Society." The music was really by Walter Raim (of folk group The Harvesters) and Stan Green, likely released in late 1966.
Tishman is alas, not actually on the album, as all of his compositions were ruined when he got seasick on his way to America on the Mayflower.
The liner notes were written by professional liner notist Tom Carlson.