My little guild supplies the fabrics for our charity quilts. We have fabrics donated from manufacturers and individuals. We obtain grants to purchase fabric (usually at JoAnn's with a coupon). If someone(s) placed such a restriction on me, I would be looking for a new guild. Do not feel pressured. If you wish to remain with your guild and participate in the charity quilts, make your quilts with whatever materials you have. If they do not accept your quilts, then donate them yourself.