For some of the animal or doll patterns, a backstitch is used to create the mouth and other facial features.  

To start sewing the backstitch, begin from the underside of your fabric (the wrong side) and come up through the layer of fabric. Your first stitch will be forward. After that first stitch, you're going to stitch to the right. Your needle will then travel underneath and come out ahead of where the thread is coming up by the fabric.