Yarn: Cascade 220
Needles: US 7, 16" circular
Gauge: 4 1/2 sts/inch in st st.
Pattern: My own, more or less. I cast on 100 stitches, worked in a K2P2 rib for 9 inches, then did one decrease round (K2tog, P2tog), worked a K1P1 rib for 3 rows, did another decrease round (K2tog), knit for 2 more rows, decreased (K2tog), pulled yarn through all stitches and was done. The finished circumference is about 18 inches, but of course it stretches quite a bit.
This is modeled by my sister Sara, rather than the intended recipient, who actually rejected the hat on the grounds that it is "too loose" and "not that warm". So if you want a green wool hat, let me know; it's up for grabs.