Great Seal of the United States Plates

I have 2 plates, which have been handed down in my family, that have the Great Seal of the US on them. I am curious how old they may be. The eagle has 9 stars above it, 7 arrows in it's right talon and 3 leaves on an olive branch in it's left talon. Each plate is 6 inches in diameter. One of the plates has a small letter D stamped on the back.