My 3 1/2 year old loves her "soft" (she named it) which we refer to as her crib bumper. Ever since she was a little tiny baby she fell asleep gently caressing her "soft", till this day this is what she does - oh, and she also knows what position she wants certain parts of her soft to be in, has to work with the position she likes to lay in. I've tried changing it around and it's though she can't find her "spot" if it's been moved around.
Now, she's not in her crib anymore, she's been in her twin size bed for a while now but, we had to attach her "soft" to her big girl bed. She was lucky we bought a bunk bed but, only needed to use the top part with the front side rail (at floor level) so this helps in holding up her soft. I'd like to take this rail down but, this would mean she'd loose her soft and she's not having it! This is totally her comfort zone. I'm guessing she can just hold on to it in her bed once I remove the front rail but, it definitely will not be in the position she likes. I'll just keep the rail up a little longer, I like that she finds something so simple sooooo very meaningful to her.
My son is 2 and likes to carry around and also sleep with baby wash cloths (about 3 at a time). He loves the feeling of those little cloths we normally put under their neck when newborn and drinking a bottle. He's been on a sippie cup since he was 18 months but, I can't store all my baby wash cloths because he uses them in this sense. He moves around in his sleep and reaches out to find one of his little cloths, I usually position them for him through the night when I check up on the both of them. Again, I like that he finds comfort in this, the only problem would be when my daughter takes them away from him to use as a blanket for one of her babies:)