That is still a very lovely quilt. This Butterfly pattern is from the 1930. I know one can't put a price on a piece of your heart, I think I would put down 4oo.oo
Another think my Granny swore by rubbing a slice of lemon into the spotsand air outside. Be careful as the sun will fade the darker colors. It seems the mold is on the back. Best of luck to you and your quilt. God Bless.