Missing Crown Molding

There is no original crown molding in our house, because all of the ceilings in our house have been repaired/replaced by someone at some time. We don't know much beyond that. However, the hallway does give us some clues as to what it may have looked like. The hall is the only room that has not been drywalled, and still has awesome textured plaster. At the top of the walls and below the replacement crown you can see how wide the crown used to be, and that there were some sort of corner detailing at every inside and outside corner. That brings me to the question. Can anybody out there give me some clues on what these corner pieces may have looked like, and, where/how I might go about finding/building replacements. And what is the technical name if there is one for the corner pieces. I have looked at alot of molding/millwork sites and so far can't find anything that looks right. If anyone out there has molding with this sort of corner detailing I would love to see pictures. Thanks in advance.