Crochet in worsted weight, with sport weight for centers.

Pattern suggests:

48 oz. black
1.5 oz each of 24 different colors (for flower petals).
2 oz. each of two different shades of yellow

Per hexagon:
1.25 yards sport weight for center
8.5 yards per petal round
4.5 yards per contrast round
20 yards per black background

Seaming diagram included.