Taking the larger circle, I sewed on the brooch mount.
You may be tempted to use hot glue.
Hot glue doesn't like metal, long term. Sewing holds it closer and looks so much better.Sandwich the leaf (make sure it's where you want it in relation to the brooch mounting pin) in between the two circles and whipstitch around the smaller circle, joining all three felt pieces.When flower is dry, use tiny stitches with floss to attach petals to the felt. You want the petal tips to have free movement, so stitch around the edge of the larger circle and leave them free. Just make sure you stitch into each side of each petal to keep it lying flat.Here you have it!
I used a size G crochet hook and worsted weight yarn. Any variations with make the flower larger or smaller.