Okay, now if you can't think of uses for these, you probably aren't on Etsy, right??? I couldn't believe my luck when I found these in, guess where???? the floral section of a kind of fancy nursery, you know, the expensive area where they have house plants, too expensive pots, etc. Well, these are BIG (see nickle for comparison), generally clear which is unusual in any glass made for floral design (there are a few bubbles, imperfections), quite flat on the back.
I'm using mine in two different ways - first to attach paper and fabric images behind with diamond glaze which never causes the ink to bleed; the glass magnifies the image and makes it really pop through the glass. the other really cool use - I'm going to make "looking glass" observation windows for shrines, where you can peer through and see the illuminated image/statue that is the central focus of the shrine. These work great for this. I'm sure you can think of other things as well. The largest of the three is almost 3" across.
I'm including a picture of how they look when they are finished so you can see for yourself how they might be used.