Don't know how to date them, but you are right these are treasures. The quilts are super. You said, "2 of my grandmother's hand pieced and hand quilted quilts to be sent to her great-great-granddaughters". How many do you have? This is awesome to have something made by your Great-Great Grandmother. WHAT A PRIVILEGE this is for them to have something that she touched. You have given them a great piece of their history. Hope that they appreciate them. Thanks for sharing. BrendaK