I have a “security blanket” too, but it’s a pillow I was given as a small child.

I’ve also felt ashamed for sleeping with it, it feels like it makes me infantile or not grown up, so I put it in a closet for many years. The past year or two, though, I’ve realized the comfort is more important to me than feeling ashamed, so I sleep with the pillow every night, usually I hug the pillow and sleep with it against me. It’s one of the few such comforts, and nothing else comforts me like it - even other pillows or plushes I have tried.