Pretty handkerchiefs were treasured among Amish girls. There were no rules pertaining to them unlike almost every other aspect of our life. They provided a tiny bit of self expression which was a welcome change.
Both boy and girl toddlers often had handkerchiefs with fun designs. My brothers each had several with various barnyard scenes, while I had one with bunnies.

On a side note, does anyone have any idea how to restore fabric that has developed spots from being stored? It looks a lot like foxing in old books. I'd love to take care of it if possible.

It was used to make a "mouse". It was always satisfying to create it, but even more satisfying to pull its tail and have it turn back into my handkerchief ready to be made into a mouse again.
Unlike the twin babies in a cradle that I used to fold it into and rock and play with for a while, there really wasn't much to do with a mouse other than give it to my baby brother and let him pull the tail to undo it, and then make another one for him to repeat the process.
I had no reason to use my handkerchief that day, but the knowledge of it being in my pocket felt good.

Mom encouraged me to save my prettiest ones until I turned sixteen and joined the youth. I was glad I had and by then I started matching the color of my handkerchief to the dress I was wearing. Except when I wore black, then I always paired a pink handkerchief with it.