Silver plated copper round tray

Have a few pieces of this set, but would like to purchase the other pieces. Can anyone give me and idea of what 'brand’s to search to look for other pieces?
fingers crossed pictures attached! Thanks so much for any help!

This mark has been seen before but has never been identified. See Silverplate Marks - Initials M - Online Encyclopedia of Silver Marks, Hallmarks & Makers' Marks.