It could be a blankie, a bear, a towel, a bottle of Jack, whatever a kid needs to get herself to sleep, the anchor that helps ease the development of her distinct sense of self apart from her parents.
According to Be Prepared, it's ideally something that you can stock up on, have a few replacement for, if necessary.
For us, it's any one of a dozen flannel blankets my mom made for the kid, which we started rotating immediately after discovering that she (the kid, not my mom) would fall asleep clutching the embroidered edge.
For Jennifer Steinhauer's 11-month-old daughter, it's the one-of-a-kind scarf that gets left on the bus.
Boy, there's no end to the poignancy of living in NYC that the Times reveals to its readers. Lost blankies, the need to choose whether to go get a Brazilian or take your baby to storytime. Life in the city is just hard. Good thing I live out here in the Rust Belt, where all we have to worry about is the economy.
My son's is a completely bland, mass-marketed carter's blanket from Target. Thank the lord for that, because he also has a hand-crocheted blanket and a hand-made quilt available to him, but they never caught on.