The legend in my family is that when a relative named Baum was asked their last name their accented reply sounded like Bum. The immigration officer (I don't remember if this was in England or the US) told them that it wasn't a good thing to be a bum in the new country and decided they would be Tannenbaum. I doubt the accuracy of this story especially given how other tall tales are common in my family. (One relative tutored the Czar's daughter, while another swam across a river or maybe the Atlantic with a large golden clock under their arm!) There's probably a small amount of truth at the core of these stories that is embellished greatly by generations of imaginative story tellers in the family.
