I think this original was raw edge applique. It is probably best to cut the petals from fabrics fused to iron on stabilizer. If you want to get compulsive, make the petals 1/4" larger and turn under the edges. I wouldn't, since you want to duplicate a wonderful existing quilt. Another nice variation is to make each petal as its own little sandwich, sewing right sides together with fairly sturdy stabilizer, clip the seams, turn the petal right side out pin it in place under the circle and sew it down. That would make a 3D flower. Not what you want tight now, but you might enjoy doing it on another quilt.