He sounds like a good husband and he is certainly a good quilter.
I'd just explain the problem you're having and ask him to drive with
you to the local quilt store to help you try to find a matching white.
He probably thought he was being helpful in using up scrap squares that
you didn't want and had left unlabeled.
My daughter loves sushi and I use her take-out trays with covers to
corral my squares.