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.
Such a simple thing, but a little hand painted stone (painted by you of course!) could be such a gift from the heart and costs next to nothing! (nothing if you already have a bit of acrylic paint and (Diy Garden Rocks)