A “Mother’s Ring” which is both of their birthstones. You can get some that you can add to if you plan more babies along the way.
My suggestion, since this is a really new baby, is to give her an entire weekend of as much sleep as she wants. I’m not kidding. I was wiped out the first few months after Kalhoun, Jr. was born. Take every feeding and changing for the weekend and let her saw a log.