There's a bunch of free patterns on any yarn website (Lion Brand, Paton's, etc) as well as
www.Ravelry.com. I found this one on the Lion Brand website (Pattern #: 40534K). You could use hats you already have and knit the heart earflaps, then just sew them on the hats. Here are the directions for the earflaps. Ignore "CC1" and "CC2". That means contrasting colors. This calls for US size 10.5 needles but you could use a 10 or 11 if you can't find 10.5. I don't check BYC often but I'd be happy to help you with the instructions. Feel free to email me if you need help. Good luck!
HEART EARFLAP Make 2
Using yarn from inside of ball, with CC1 and larger needles, cast on 3 sts. Using yarn from outside of ball, cast on 3 more sts onto the same needle 6 sts. **NOTE: MY YARN ALWAYS TANGLES SO I'D USE TWO SEPARATE BALLS**
Row 1 (RS) *[K 1, M1] 2 times, k 1; repeat from * on second set of sts 5 sts each side.
Row 2 and all WS rows Purl.
Row 3 *K 1, M1, k to last st, M1, k 1; repeat from * on second set of sts 7 sts each side.
Row 5 (join sides of heart) K 1, M1, k 5, k2tog, k 5, M1, k 1 15 sts. Cut 2nd yarn.
Row 7 and all RS rows through Row 15 K 1, ssk, k to last 3 sts, k2tog, k 1 (2 sts decreased each row) 5 sts remain after Row 15.
Row 17 K 1, slip 1, k2tog, psso, k 1 3 sts.
Row 19 Slip 1, k2tog, psso 1 st.
Fasten off. Weave in ends.
FINISHING
With CC2 and large-eyed, blunt needle, work blanket st around edges of Heart Earflaps. Sew Hearts to sides of Hat with top of Heart sewn to edge of Hat and bottom of Heart dangling down below the brim.