With A, ch 35. Being careful not to twist ch; join with sl st in first ch to form a ring.
Note: If you find it difficult to join the beg ch into a ring without twisting the ch, Rnd 1 can be worked as a row, then joined into a rnd, as follows: Leaving a long beg tail, ch 37, hdc in 3rd ch from hook and in each ch across; join with sl st in top of beginning ch - 35 hdc at the end of this rnd. Use yarn tail to sew gap at beginning closed.
Proceed to Rnd 2.
Rnd 1: Ch 2, hdc in each ch around; join with sl st in top of beg ch - 35 hdc at the end of this rnd.
Rnd 2: Ch 2, hdc in each st around; join with a sl st in top of beg ch.
Rep Rnd 2 until piece measures about 9 in. (23 cm) from beg.
Fasten off, leaving a long yarn tail. Thread tail through sts of last rnd and pull to gather. Knot securely.
With A, ch 125.
Row 1: Dc in 4th ch from hook (beg ch counts as first dc) and in each ch across; change to B in last st - 123 dc at the end of this row.
Row 2: With B, ch 1, sc in each st across; change to A in last st.
Row 3: With A, ch 3 (counts as first dc), dc in each st across; change to B in last st.
Rows 4-7: Rep Rows 2 and 3 twice more.
Following package directions, make a medium size pom-pom with A. Tie pom-pom to top of Hat.
Weave in ends.