Your sunflowers are SO pretty, Lizzie3!
Your kitten is cute, too.
For what it's worth, there's no indication that you had any trouble at all with your circles, or that your plates aren't nice and flat. Good job!
Next time for your circles, instead of pinning the circles on, you could press your plate and circles very flat, then apply Elmer's Purple School Glue stick to the back of a circle and position it on your plate, pressing well to set the glue.
It's fairly easy to remove the circles and reposition if you want to, you can iron right over a blob of wet glue and it won't stick to your iron. No pins to sew around and pucker up your fabric. I buy these glue sticks by the case - I use them for every kind of basting in quilting and apparel sewing. (Not so much for bags - I use Fabri-Tac for that because bag material are sturdier and pull apart easier.) But, it's really great stuff for applique, in particular - and I use two or three tubes of it to baste the binding on the quilt, first the front, then the back. They should give me rebates.
Congratulations on a CUTE Dresden top!