plain white fabric I had, two different quilting threads (grey and yellow) at the Cotton Patch.
Not sure you can see the quilting (it should be more obvious when hung). The idea was to have concentric squares so it looks like a painting (or an excuse to indulge into my obsession for geometrics. Depends who/when you ask.)
I am actually really pleased with it, despite my few issues (alignment of the small squares not that straight, quilting issues). Well, at least it definitely looks homemade!