I second the stuffed toy that plays a lullaby.
I was given a stuffed dinosaur that plays “you are my sunshine” when I was born. We were inseparable for a few years, then I would still cuddle it every night for a few more years, and at 21 years old I still cherish it. I almost had a nervous break down when I thought he was broken (his neck also moves from side to side a little with the music), but luckily it was a false alarm. I loved him so much I took good care of him; his scales are a little worn from when I sucked on them for comfort as a baby, and the material a little worn around the winder for the music, but otherwise in mint condition and still plays perfectly. I named him “Rexaur” because I couldn’t say any of the real dinosaur names so mashed them together. I might share him when I have my own kids, but I think I won’t be able to and will keep him forever as my own special thing.
I’d think a good quality toy with a nice tune would be perfect :)