In English notation, so remember if you're American if the pattern says treble crochet, do a double crochet, etc.
Notes: I changed colours and finished off every round. If you don't do that - you're working in one colour, etc. then you'll have to add a few slip stitches to the start of each round to get you to the chain space.
To do the first treble in the new colour, make the slip knot on your hook, hold in place with your index finger, yoh, push through stitch, yoh, pull through 2 loops, yoh, pull through 2. No chaining required.
Bobble: is basically a tr2tog but into 1 stitch instead of 2, so, yo, insert through st, yo, pull through st, yo, pull through 2 loops on hook, yo, insert back through same st, yo, pull through, yo, pull through 2 loops on hook, yo, pull through remaining three loops on hook.
Gauge: foundation round & round 1 = 6cm / 2.5 inches
Foundation round: ch4, tr into first ch, ch 1, *work 1 bobble then ch 1* repeat 5 times. sl st into top ch of the ch3. Fo
Round 1: *3tr in ch sp, ch2* repeat 6 times, join with sl st, Fo
Round 2: *3 tr, ch2, 2tr in middle stitch of treble cluster on previous round, ch2* repeat 12 times, join with sl st, fo.
round 3: *3tr in ch sp, ch2* repeat 12 times, join with sl st, Fo
round 4:*3 tr in ch sp, ch 3* repeat 12 times, join with sl st, Fo
round 5: *3tr in ch sp, ch 2, 3 tr in first ch of next ch sp, ch 2, 3tr in last ch of sam ch sp* repeat 18 times, sl st to join, Fo
round 6 - 13: *3 tr in ch sp, ch2* repeat 18 times, sl st to join, fo
round 14: in colour A: *dc in first st, ch3, sk next 2 st* repeat 30 times. sl st join, fo
round 15: in colour B: working into round 13, dc in stitch next to where you started with Colour A. *ch 3. remove hook from last loop, push hook through the chain sp from colour A, push hook back into last loop of chain and pull the chain through to the front, ch 3* repeat around. Note: every time you chain 3, the first chain will trap the chain from Colour A.
Foundation round in Yellow colour for centre of flower: ch 3, 9 tr into first ch, join with sl st to top of ch 3, (10)
round 2: ch 1, 1 dc into same stitch, 2 dc into ea st around, join with sl st, fo (20)
round 3: in new petal colour, inserting hook into front of stitch only: *ch 3, dtr in same st, 2 dtr in ea of the next 2 st, 1 dtr ch3, sl st into same st, sl st in next st* repeat 5 times, fo
round 4: start this round in the middle of one of the petals from previous round, in second petal colour, inserting hook into back stitch only: *ch 4, tr tr in same st, 2 tr tr in ea of next 2 st, 1 tr tr ch4, sl st into same st, sl st in next st* repeat 5 times, fo. Leave a long end to sew it to hat with.
This is the first pattern I've tried to write up for other people to be use, so be gentle when pointing out the inevitable mistakes please. ;)