1961 Presidents Club silver plated serving tray

Just my opinion but I would not polish. At least not until someone very knowledgeable in those types of items tells you differently. The reason I say that is because I was a collector of antique Italian stilettos for many years. When I, our another collector, looked at an old knife we wanted to see the nicks and scratches and patina that was part of its story. If you handed me a knife worth $1000 in its "been hidden in the attic for 100 years" condition and that knife had been polished and sharpened, you would n be lucky if I offered you $500. Now, that's knives, I'm not sure about your item, but why chance it?

Polishing silver will not decrease its value. Check the back for markings and post up images of them and I'll have another look.