here's a pattern using stitches you already know.

My Pattern recommends a 5mm hook.

6 Chain and join into a circle with a slip stitch.

Foundation round - 2chain and then work 15 trebles into the centre of your loop. slip stitch into top of 2 chain to join.

1st round - 3 chain (1 treble, 2 chain) 15 times slip stitch to join.

2nd round - 3 chain, 1 treble into same space (1 chain, 2 treble) into next three 2 chain spaces 3 chain *(1 chain 2 treble) into next four 2 chain spaces 3 chain. rep from * twice 1 chain slip stitch to join.

last round - 1 double crochet into each treble and chain space (working 4 double crochet into each corner chain space all round slip stitch to join and fasten off.