This may not be exactly how I thought my sister would wear her new hat:
I had so much fun making this -- the yarn is Malabrigo worsted, color Glazed Carrot (the most perfectly named yarn ever). Cell phone photo in not-the-best light does not do it justice. The pattern is here on Ravelry, and a good tutorial on intarsia in the round is here (I tried a bunch, and this one worked best).
The face is a little bit scrunched up because my yarn worked at 5 sts/inch rather than 4 sts/inch -- but all pumpkins are different anyway.