Kristen's lullaby has reached the professional level.
What's the most popular lullaby in America?
It's a lullaby that was sung for me when I was little.
A song you sing to protect your child while they sleep is called a lullaby.
The readings for this word are all kun'yomi readings. You haven't learned this reading for 守 yet, so here's a mnemonic to help you:
When you finish singing a lullaby to your child they always ask for more (もり). It doesn't matter how many you sing, they always want at least one more before they will fall asleep.