Your simplest option is to look for a plain t-shirt with an American flag design on it. It could feature a soccer ball to, but you’ll have to keep your eyes open for shirts like this!
Although rare, there are some shirts out there made with an actual American flag. It is not technically correct to do this to a flag, but the option is there for you!
A great gift would be a USA national American soccer team t-shirt or jersey. These shirts often have the design of a flag on them and are great for showing your spirit in your country!
There are also used soccer jerseys available that have been worn by your favorite players, some even autographed. These sure beat the socks off regular autograph soccer balls!
While these are all great idea, if your budget does not allow it, as these are more expensive options, then a regular American flag t-shirt is nothing to be ashamed of. You should wear it proudly!