1) Self-adhesive pin backings (available in the Jewelry making section at Michael's, $2.99 for 26 pcs)
2) Wooden circular disks (I found soccer balls and beach ball wooden circles on clearance at Michael's, $.29 each)
3) Printed images of your buttons the size of your wooden circular discs (I used the exact size of the image at the top of this post)
4) 3M Re-positionable Spray Mount (this stuff is AMAZING)
1) Cut out all your circles so they're ready to go.
2) Remove sticky backing from your pin backings and attach to the middle of the side you don't want to show (i.e. I put mine on the soccer ball side)
3) Spray the spray mount on the back of your paper circles.
4) Quickly adhere the paper circle (careful to align it upright with how the pin backing is attached - so it will be easy to pin on) to the OTHER side of your wooden disc.
5) Repeat and presto! Birthday buttons.