I used dk and a 3.5mm hook, any yarn and appropriate hook will do but this combination made the poppy about the right size.
The Red Bit
Round 1 - Make a magic loop, make 10 sc in loop and close it up tight, join with ss.
Round 2 - *ch1, sc, ch1, 2dc in next st, 3dc in next st , (2dc ch1 dc) in next st, ss in next st. rpt from * around and join with ss.
Round 3 - *ch1 3sc in next 2 sts, 2sc in next 5 sts, 3sc in next 2 sts, ss in next 2 sts. rpt from * around, fasten off.
The Black Bit
Make a magic loop, 8 sc into loop, tighten and fasten off.
The Green Bit
Round 1 - ch10. work sc in 2nd ch from hook then in each ch stitch as follows.. hdc, dc, dc, trc, trc, 2trc, hdc, dc.
Turn and work back along other side of starting chain as follows.. 4sc, sc, hdc, 2trc, trc, dc, dc, hdc, sc, ss and fasten off.
Sew in the ends attach the black centre to the red flower and then the leaf to the back (careful to only catch the back of the stitches so your sewing doesn’t show through)
I left a long tail on my red yarn and used this to attach a safety pin, I guess you can attach it to your person however you like.