Last week I picked up a big bag of someone's hand dying fabric binge at the thrift store. I recognize what it is because I had one of those once too...
Not enough neutral/pales, so maybe I'll tie dye/tea dye some solid white 100% cotton fabric I have to make those. It was a heck of a deal I wasn't going to pass up (the entire bag was only $7.99!) and it seems to me pretty darn perfect for this project. I find some wonderful things in my thrift shopping.
I also have another lady in my small group who went through a hand dye phase, will ask her if she has any lights.
I do also have a nice light tan/yellowish batik for a consistent neutral... it is definitely more patterned than the hand dyes, but it is subtle.