WM Rogers Tea Set

I just bought a WM Rogers tea set.  The only marking on it is the eagle and star with WM Rogers.  I have searched online and only found one set that looked like mine.  Most sets have four legs on the bottom of the pieces.  However, mine has a single round stand under the center of the pieces. The ones with legs were going for $40-$100 while the only one without legs was $475.  This sparked my interest.  I only paid $20 at a flea market for the set, and I plan on keeping it for display at my home no matter the value. Also, it seems I am missing the platter that the set goes on.  However, I plan on finding the piece that completes it.   The first question I have is how can I tell if the piece I have is coin silver or silver plated?    The second question is, what are the possible values of my set?  Thanks for the help!