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.
Free Quilt Block Pattern
The Rosebud quilt block is a four patch which also makes good use of the half square triangle unit.
The quilt you make using this block would look spectacular if you chose to use up your scraps. The resultant quilt would give the idea of a garden, since you would have a variety of "roses" displayed.
The sample quilts illustrated give you an idea of how different your quilt will look simply by using a different setting of the quilt blocks.