Trying to find a certain newfoundland breeder..?

Check with your local kennel club or the national kennel club. AKC or whatever the national one is for where you are. If she is a good ethical breeder chances are she may be a member of the parent club for Newfoundlands. Also, if it was years ago she came to your attention, she may have moved, so don't hesitate to look at others, you may be able to find her.