Aren't these cute? I have been wanting to make some of these...
You cut strips of the felt, the wider the strip, the taller the flower. The shorter the strip, the smaller the flower. Taper each end in width to create a realistic rose appearance.
Now roll them up, experimenting with how it looks, if you don't like it unroll it and either trim or change the end you start the roll with.
Next cut a square (or you can cut a circle) a bit bigger than your flower, in the same color felt.
Next put a glob of hot glue just a bit smaller than your rosette on the square.
Now, keeping your fingers away from that hot glue, gently push the back onto the rosette.
Apply a dot of hot glue under neath the end of the felt strip and remove the straight pin.