can’t crochet (yet) but found this pattern for knitting flat circles:

Cast on 8sts and arrange on 4 needles

Rnd 1 and every following alternate round: Knit
Rnd 2 (increase rnd): Knit into front and back of every stitch. 16sts total
Rnd 4: (K1, knit into front and back of next st) 8 times. 24sts total
Rnd 6: (K2, knit into front and back of next st) 8 times. 32sts total

Continue, working one more stitch between increases on every increase rnd.