I saw a beautiful Dresden plate done this way: each plate contained only two fabrics for the "petals"--a focus fabric and a solid fabric. For example, one plate was a focus fabric (a chevon stripe of different colors) combined with orange. Another plate was the same focus fabric with teal- another plate was the same focus fabric with tan, etc. THen you could use another color for all the centers.
Clear as mud? Hope you understand what I'm trying to describe.

How about Bali Blenders? I just looked up quilt fabrics and saw how pretty they are and they progress in color as well as texture - mottle. Yellow as the center would be pretty. As another mentioned, brown is the only other color I can think of that would go with the tan, teal, yellow and orange. Although, if you used teal as the center, I'd use that as the boarder too. I'm not sure what the cornerstones would look like - can't picture that, so I'm no help there :( Perhaps a different shade of teal? That way, the quilt would seem like Fall with a bit of water around the edges.

I did my centers the same as my background. I wanted it to look like an antique on I had seen with no appliqued center piece.

If it were me, I'd take her shopping if possible and at least but a few pieces in colors she chooses. You can take those pieces and do the big shopping yourself. If she can't shop with you, send her a link to an online store you like. Have her put some items she likes in the "cart" and send the link from the cart back to you. That way you will have a really good idea of what she likes to work from.

Check this out: http://www.pinterest.com/quiltinspir...-plate-quilts/

Also, the plates made with Kaffe prints would work without much trouble trying to match colors. Would be a gorgeous quilt. (Where's my bucket list!) lol

Dark Brown for the centers, ivory/cream for the background, dark brown sashing and teal cornerstones.

I also had as my first thought was for dark brown for the background.

Google modern dresden plate quilts and look at google images. There are a number incorporating those colors.

Maybe a cream back, a rich brown and a green. Go to fabric.com, pick some fabric and put them on the design wall. Then you can see them together. Or maybe your DGD could go and pick out what she wants.

I also like the variegated color for each plate. For the center circle, what about a white on white that has sort of a 'lacy' design that could represent her wedding dress?

I would also go with different shades of your 4 main colors. But if you want to add one, I agree with chocolate brown.

Some of the more modern fabrics have those colors in them. Find a large print at your LQS and go from there.