I also like the gray circles. I like your quilt too. It is just pretty nifty looking! I don't have any advice for the washing question. I have never made a rag quilt, but my sister always takes hers to a laundry mat and uses one of their extra large machines. I think I would be afraid to wash just the top of one of mine....it would probably all fall apart.
But....I really know nothing about the washing part, so I hope someone else has a better reply than I do.
Again, I your quilt is wonderful!!
Dina