You will need two crochet hook sizes, worsted weight yarn, and a stitch marker. I used size K for the main part and size G for the brim.
Abbreviations:
ch = chain
sc = single crochet
pf st = puff stitch
Puff stitch: Yarn over, put the hook through the stitch, yarn over pull up a loop (3 loops on hook), yarn over, put the hook through the stitch again, yarn over pull up another loop (5 loops on hook), yarn over and pull through all five loops, ch 1 to secure the stitch.
Main part of hat:
With size K hook, start with a magic circle.
Rnd 1: Make 6 pf st in ring. join.
Rnd 2: ch 1, 1 pf st in the same stitch and each stitch around. join to top of first pf st. (11 pf st)
Rnd 3: ch 1, 1 pf st in same stitch and in each stitch around. join to top of first pf st. (21 pf st)
Rnd 4: ch 2, 1 pf st in next stitch (it will be the stitch in between the pf stitches) *skip next st, pf st in next st* repeat between *s around. join to top of ch 2. (21 pf st)
Rnd 5: ch 2, pf st in same stitch, *ch1, pf st in next stitch in between pf st* repeat around. join in top of 1st pf st. (21 pf st)
Rnd 6: ch 2, pf st in space between pf st, *ch1, pf st in next space between pf st* repeat around. join in top of 1st pf st. (21 pf st)
Rnd 7-12: repeat row 6.
Brim:
The brim is crocheted tightly with a G hook. If you have trouble crocheting tightly, use a size F hook. This is the tedious part and a little hard on the hands. After the first row, you won't be joining anymore, so the brim will be seamless. This is where your stitch marker will come in handy.
Rnd 1: ch 1, *2 sc in space between pf st, 1 sc in top of next pf st* repeat around. join in 1st sc.
Rnd 2: ch 1, 2 sc in each stitch around. mark your last stitch.
Rnd 3: 1 sc in each stitch around. move your marker to this row.
Rnd 4: *1 sc in next 15 stitches, 2 sc in next stitch* repeat around. 2 sc in last stitch, move marker.
Rnd 5: *1 sc in next 16 stitches, 2 sc in next stitch* repeat around. 2 sc in last stitch, move marker.
Rnd 6: 1 sc in each stitch around, move marker.
Rnd 7: *1 sc in next 17 stitches, 2 sc in next st* repeat around. 2 sc in last stitch, move marker.
Rnd 8: *1 sc in next 18 stitches, 2 sc in next st* repeat around. 2 sc in last stitch, move marker.
Rnd 9: *1 sc in next 19 stitches, 2 sc in next st* repeat around. 2 sc in last stitch, move marker.
Rnd 10: 1 sc in each stitch around, move marker.
Rnd 11: repeat row 10.
You can end here or if you would like your brim wider, continue to make increase rows similar to rnds 7-9. Your next increase rnd will be *1 sc in next 20 st, 2 sc in next st.* Add rnds like 10 and 11 to keep the round shape.
