I saw a brief picture of an end table and the top was an old tray from a silver plated tea service set. Looking for unique ideas on what to put under it and how to attach it. Please help!

Find yourself an old "treddle sewing machine" base.

One could cut a hole in a table top, smaller than the silver tray, but in the same shape, then mount the tray under the cut top. Several Off-set metal mirror clips can be screwed to the underside of the table top to hold it up against the underside. If you have a piece of glass cut to the size of the table top, then you can display shallow items in the tray, and still use the glass top as a flat surface?