Military Plate - WWI Canadian regiment

This is a plate I was told by family belonged to my father who fought in WWI in a Canadian regiment, and this was some sort of military plate his regiment had. It has a lot of detail that's hard to see in the photo but which is an engraved pattern that borders the main upper side. The plate is in bad shape that could be fixed if it was molded back to its original shape by someone who specializes in repairing metallic objects. I tried to clean off the grime of almost 90 years with some metal cleaner, and this is why there are 2 large spots where it rubbed through to reveal what looks like either copper or brass. I am interested in anyone's comments on how to research this further, or if you think it might be worth more as a collectible item from WWI if it turns out this is copper, or would it be worth more just for its copper value or other metal value?