Button cookies - love this idea! You need a shortbread (butter cookie) recipe, two biscuit cutters (one slightly smaller than the other), and a drinking straw (to make the holes). Aww, cute as a button!
These remind me of mandalas. We could get stones and do mandala zendoodle art on them, and then write a simple encouraging message on the back for baby girl. Make a nice fabric bag for her to keep them in.