I made some with clay once and they were lovely. However I didn't use a varnish that was good for this I guess, they always stayed a bit sticky as if they were never dried. That was around a year ago. I hated to, but had to trash these. I loved the look of mine. I had grown these tiny purple flowers and dried the spent flowers. Did that all season long. I added them to the clay, and carved the lettering out with a popcicle stick (cut to a size I wanted and used the width of it too). I added a single, full pressed flower on the backs and then baked. Then turned out so pretty.
Some people believe you shouldn't seal them with any varnish as they are "breathing", taking in energy. They had a soft, powdery feel before the varnishing. I hate that I ruined them with the varnish. I don't live where I did, and so no garden to dried flowers with. I may try to get a few this spring and summer to maybe do this again. I think this time, I will only seal the fronts, if at all.
To get a mental picture of what mine looked like, think of what the dried floral papers look like (you know you see stationary and cards as this sometimes. It was like that look, only these were white-creamish stone. The stones looked like tiny oval biscuits and the lettering was deep into them. I used a gold for the lettering. Ahhhhhhhh I am missing them. Kept them forever before throwing them away.