This idea is close to my heart because I did something similar for my wedding. To ask each girl to be in my wedding I had vintage handkerchiefs embroidered with their monograms and then wrote little notes. I liked this idea because it gave the girls something useful to use on my wedding day. I only wish I would have asked my photographer to take a photo of all of our hankies!
I also love this idea of tying a cute little stamped note to each hankie and giving them to the bridesmaids (or moms, or even guests) on the day of the wedding. Oh how I love details!