Those sunflowers are very pretty!
I'm another that uses Elmers washable glue. I've used a couple of other "generic" brands but find Elmer's is softer and works much better. It also seems to release easer when I need to remove something. I even use it to stick my fabric down to the stabilizer when doing machine embroidery (I don't hoop the fabric, just the stabilizer).
For the plates - a trick I do is sew them in quarters, so if I've got 20 petals, I sew them into groups of five. Then I square them up which helps take out any excess in the middle so they lay a lot flatter. I've been using the appliquik method for the circles, and just ordered the larger size "perfect circles" so I'll have heat resistant templates.
I cut out the fabric 1/2" - 3/4" larger than the template, then use washable glue and put a spot on to hold the template in place. I take a dry iron and press the excess fabric over the edge, maybe by 1/8" to 1/4". I do not try to iron the excess flat, I'm just pressing a firm crease in all around the edge. Then I remove the template and trim the allowance to a scant 1/4". It's much easier to press with enough fabric to hang on to, and trim afterwards.
Then I use the small glue pen that the appliquik uses (though a cheaper brand) and use pointed tools to glue the pressed edge down, working in the excess fabric. Once done I press it good and starch it (about the only thing I use starch for.
Then I lay out the plate and press it again so it's good and flat, get the circle in the right spot, and flip over a spot on the edge and glue, and work my way around the edge. I sew them on by machine using a narrow zigzag and invisible thread.
I finished all the plates for the RR quilt , and have them sewed to the corners so the next step is sewing the corners to the quilt (I turned it on point). I'll share pictures when that is done.
I'm looking forward to starting my Dresden Plate/Doily quilt top. I have a spot in my office where I can hang a 60x60 quilt, so that is what I'm going to aim for.