I don't mean to confuse the issue, but I was told:
A Fat quarter is essentially a half yard of fabric, split at the fold. Thus you have 18 inches in length, but 22 inches in width. So when you press the fabric you will be folding the selvege edge to the center (fold) cut before cutting.
I also prefer to wuy a whole yard and keep the remainder for another quilt at another time....or for making pot holders, etc.
Please correct me if this is incorrect. A long-time hand quilter gave me this information and I was sure she knew what she was talking about. She could be wrong, I could be wrong and now we are all confused.