Great finds. Now do your self a favor. Do not clean until you have had a chance to decide if you want relics or clean chuncks of metal. I still have my first plate which I cleaned until I could eat off of it. I wish I hadn't. Assuming you will find other buttons and plates, they will all have their distinctive coloring and patina. I enjoy the differences and keeping them as they came out of the ground. I would wash the loose dirt off with water and tooth brush for the plate. The Mass button may or may not have gilt left depending on the soil. If it does have guilt then it will be beautiful if cleaned lightly. If not, it will be ugly and brown. If you leave it as is, you can see years from now what you saw when you dug it up. Just my .02 worth.