On the lighter side...
While, strictly speaking, the following song is technically not an American patriotic song, it does refer to the headwear sported by such luminous Americans as George Washington, Ben Franklin, and many of their contemporary buddies, so the Americans who wore them back then is what sort of gives this song a patriotic aspect, so I that's why I thought it could be included here.
Mein Hut, er hat drei Ecken.
Drei Ecken hat mein Hut.
Und wenn er nicht drei Ecken hat,
Dann ist er nicht mein Hut.