i have no idea... maybe start with a chain, tensioned tightly, place holder and lock stitch,ss or slt and continue with chain and use 2 beads with down picots for the eyes, this chain will have light tension, join to start of chain with lock join, continue to chain with light tension and join to the second place holder...or....simply a ring with 2 down picots with beads and halfway across the ring a series of down beads for the mouth...i will try both to see which looks nicer. but there are a couple ideas.
There are some 'emotitats' on my page here http://www.janeeborall.freeservers.com/EmotitatsSmll.pdfThey might help.
My first thought was "Frivole's Happy Heart"! It has the smile and you could add two beads to complete the face.https://docs.google.com/file/d/0B2SUi2Rbut3JMGZkNzJlNWYtNzVkYi00OWQ5LWEzNGEtNDY2NmE3ZTk0M2Fi/edit
My grand daughter shoved something in my face when she started tatting saying it was a smiley, she had not learnt to use beads so it was just chains. I have no idea where she found a pattern or if she made it up herself.Margaret