Are you interested in Vexillology?
How about Philately?
How about the first U.S. stamp show the image of the Stars and Stripes?
This thirty-cent stamp was printed in 1869 and used primarily for mail going overseas. If you want to buy one today, it will cost you about $350.
Read more about this first U.S. flag stamp at the U.S. Philatelic Classics Society, Inc.