If you divide your sts onto two needles (one can be the circular needle and the other can be any needle that's close in size). Then orient the sts with the right sides (outside of the hat) facing and use the other end of your circ to do a 3 needle bind off across the top of the hat. There's a video on this site
to show you how. It does make a very cute hat and the pom-poms are a good idea. Good luck with it!