The half square triangle unit is probably the most commonly used patch in a quilt block -- well it is second only to the square. It is made simply with two triangles, filling up half the square each -- hence the name. Take a quick look through this website, or in any quilting magazine, and you will start to notice that this half square triangle, regardless of its size, is present in more quilts than not.
Abe Lincoln's Platform
Free Quilt Block Pattern
Here is another example of a patriotic quilt block -- the Abe Lincoln's Platform block. Just the other day I was creating the Martha Washington Star block.
Abe Lincoln's Platform is an easier quilt block to make for two reasons. Firstly, it is made only of a few half square triangles and the rest of the pieces are squares or rectangles. Secondly, due to the math involved, it can make for a larger block (14 inches square) to make the block easily divisible by seven.
By playing around with colour combinations (don't be limited to shades of one colour as I have chosen to do), you can create totally different looks in your quilts.