If you don't have a flag to display or flag pin to wear, you can celebrate in song. Ball State's online audio resource, Naxos Music Library (Ball State login required) has several albums of patriotic music.
50 Patriotic Songs, including The Star Spangled Banner (the National Anthem), You're a Grand Old Flag, Holding the Flag for America, Riders for the Flag, and a musical setting of The Pledge of Allegiance.
If you can't remember the words to the Star-Spangled Banner, here is a scan from one of the Music Library's 19th Century song books. At the end you'll see the original words to the melody -- which was a drinking song!