If you're doing a lot of circles, Westalee has a circle ruler that makes perfect circles in assorted sizes that is quite easy to use if you've done any ruler work.

Watson

Now I can't find it but just saw a log cabin quilt with kites in the borders that was quilted in concentric circles from the center of the quilt outward with a walking foot! was wonderful!! so it can be done.

this is it. https://www.quiltingboard.com/main-f...t-t294811.html
concentric circles with walking foot! great!

Wow, that’s amazing.

So far I’m finding the circles I’m doing with the walking foot are more successful than the FMQ ones: I’m finding it difficult to get into a rhythm with the FMQ, and my stitches are terrible. But it’s almost impossible to do a small circle with the WF.

- really good! The line if my circle was so clear, and the paper came off without any trouble.

Here's my spiral quilt..... it has become a favourite on our couch and even though it was quite stiff once completed because of all the close quilting, it soon softened and now drapes beautifully. I found using the walking foot to do circles/spirals was a bit tricky in the beginning but the key is to go very slowly, stopping every few stitches to readjust the quilt, and to keep your stitches small for the first few spirals then before you know it you are sailing along.

Beautiful!

Quilting Circles
 

You can take a thumb tack, tape it to the bed of the sewing cabinet with painter tape -point up and this will work if you don't have a lot to do. You will have to figure where the center of the circle is and that is where you will put the center of the fabric over the tack. If I have a lot of circles and I am home, I use a circle attachment on the machine.
I always use a open toe foot.
If you are doing small circles, you can glue several CD together and use them as a template to sew around.

I’ve tried several techniques for sewing circles including a pricey attachement for my Viking which is more trouble than its worth. The method that works every time, for me, is the thumb tack method. I think it would work with a walking foot too. I use one of those lapel pins you get free with a flat top I’ll see if I can take a picture or find one. Either float or fuse stabilizer. You can also use a flathead thumb tack and eraser. Turn the lapel pin upside down, point up, and tape the pin so the point is a RADIUS distance from the needle. Place the CENTER of your circle over the pin point and push thru the fabric. Use the lapel pin clamp or for a thumbtack use an eraser. The. Sew any straight or decorative stitch. Gently guide the fabric and voila a perfect circle. See photos. I hope after this newsy reply that this is what you were asking. Lol