It's a basic rolled rosette made with satin ribbon instead of fabric.
I can't link the YouTube vid I use b/c I'm on my phone, but the way I learned is to cut out a circle of cardstock in the width you want your rose.
Then glue the end of your ribbon to the center. Then twist the ribbon and roll it around the center, gluing to the cardstock as you go. When you get to the edge, glue the ribbon over the edge of the cardstock for a nice finish and cut and glue the end to the back.
Then glue to your headband and finish with a felt backing, or for a clip, finish with felt and then add a clip.
Looks like the one posted in the OP was twisted and rolled inward toward the center, and she didn't worry about folding the edges if the ribbon in, so it's just a freehand "twist and roll".