This isn't really answering your question about a natural pacifier, but if you are concerned about the "addiction," I will share, for what it's worth...
I'm sure you know that babies need to suckle when they're young, so everybody is trying to figure out how to manage a pacifier/thumb/whatever. When my baby was about 4 months old (when I started napping her exclusively in her crib, not my arms), I was going to try to take it away, but a wise veteran mom friend suggested that she was too young, and instead I might restrict the pacifier only to the crib or the car. I tried it, and she was too young to be "addicted," so she didn't even seem to notice that she didn't have it when she was awake. It did and still does help her to sleep, or calm her when she's bored or tired in the car, but otherwise she's not a pacifier baby at all. The happy by-product of this is that the pacifier is now a powerful parenting tool for me. It helps her know it's sleep time, etc. And she's not addicted to it in bed either, really, (she can sleep without it) but she likes it.
I'm SOOO glad for my friend's advice, because I didn't want to have a pacifier addiction problem, but I knew that babies do need to suckle. Anyway... just thought I'd pass along the thought in case you were interested.
Sorry I don't know of a natural remedy (other than the thumb, of which I'm a fan, but they really can't figure out how to get it into their mouths until 4-6 months).