I made birthday crowns for my girls last year. I had intended for them to be a special birthday thing, that we got out only once a year, so they would be extra special. But, as these things go, the girls loved them, and they found a permanent home in our dress up basket. I had no idea how much the kids would love them. They are a regular feature around here.
I digress. The directions are below, but you can also download the templates I used. I tried to make a couple that were boyish, too - they're angular and not pink. My crowns have about a 17" circumference that will stretch quite a bit, so they're one size fits most - just use a bit more elastic if you have a big head. :)
Update: Be sure to check out the Nicholas Crown Project that this tutorial inspired! I'm giving away dress-up crowns! Come help me out!
Instructions:
1. Draw or print template, cut out. If you draw your own, the width should be about 9 inches.

3. Cut out interfacing and iron to the wrong side of your back fabric. Alternately, you can just cut a third layer of heavy weight fabric and put it in the middle of your sandwich - both work well.
4. Topstitch trimmings onto your front fabric. I used ribbon, bias tape, buttons, lace, and a handmade crocheted rose. The possibilities are endless.
5. Cut a 9" piece of 1/4"-1/2" elastic.
6. With right sides facing, sew around the edge of your crown. Leave openings on the bottom inch of both sides. You'll turn right side out through one of these holes, and later insert the elastic in each side.
7. Clip slits in seam allowance, especially in the corners. Turn right side out, poking out all the little points and curves with a chopstick/pencil thing. Iron sound that all the points are neat, and the openings have their edges neatly tucked in. Don't skip the ironing - it really helps.
8. Starting just after the opening on one side, top stitch around the crown. When you reach the opening on the opposite side, insert on end of the elastic (about 1/2"-1" from the base of the crown) and back stitch over it a few times. Continue topstitching around the crown, and repeat the elastic insertion with the other end. Be sure not to twist the elastic.
Feel free to sell items made from this pattern; however, if you do, please give credit to me as the designer.