I saw a similar idea online here. This is my take on it.
What you need:
Two 7 inch circles of fabric
Something that makes a crinkly noise, like an empty cereal package, metallic paper, clean chip/crisp package.
for the sun rays 2 1/2 inch by 7 inch long fabric.
For the sun rays, I used a jersey fabric that needed no sewing. As you can see from the photo below you need to cut the fabric out, take one piece fold in half. Cut at an angle around 2 inches; then knot the top.
I used eight pieces and laid them out first to see how it would look.
Pin the rays onto the right side of one of your fabrics with all the knotted ends placed in the centre of the fabric circle. Baste stitch them all into place. Remove pins.
Place the other piece of material on top of the material with the basted rays on it with right sides facing one another. Sew around the edge using 1/4 inch seam allowance. Leave a 3 inch opening so you can turn it right side out; I left the gap between the rays.
Turn the right side out, stuff in the crinkle material. Top stitch all around the top of the sun, closing in the gap.
This will be fully washable, but I would not put this in the dryer and if ironing use a low heat. I sewed a little homemade sun motif in the middle of the pink circle. This is light enough for a young baby to hold and they will love to chew on the rays of the sun.
The yellow material was a piece from one of my 50 cent bags I picked up from Fabricland.