Antique Sideboard Server with Mirror

I found this piece on Facebook marketplace. The seller said he had it for over 40 years. He originally purchased from an estate sale out of an old barn in Maine. He said he thought it was made in the early 1900s. There are no markings or tags. There is the remnants of a brown paper type tag on the underside. I can only make out "su". Any help would be appreciated!