Cajun Framer,
Since I haven't said so yet, welcome to the Grumble. There are lots of ways to mount plates. 1)You can sink mount them:cut a hole the exact diameter of the plate out of foamcore. You may need several pieces depending on the depth of the plate. Cut your top mat with the hole slightly smaller than the diameter, so that it covers over the edge of the plate slightly. Cut a solid piece of foam board for the backing. You ATG the backing & the surrounds together, put in the plate, ATG the top mat to the surround foamboard. You now have a plate sandwich, with no adhesives attached. The top mat will hold it in place, and keep the glass from touching it.
2) You can use plate hangers (look in gift stores or United Mf. catalogue for these) Wire the hanger through the mat & backing. All you can see are the little gold tips.
3) Use Mighty Mounts, also available from United and maybe from LJ. Depending on how deep your plate is, they offer different sizes & depths. They have mounts for lots of stuff, coins, knives, etc... and they can be adapted for other things as well.
4) You can buy premade plate frames from Bard's and Inline Ovals.
Sorry this post has been so long but sounds like you needed a few options. Good Luck. By the way, if you post questions on "How to.." on the main forum, the Grumble, you'll get lots more answers.
Leslie
Leslie