You don't say what types of fabric they are, only that they are not cotton. Many kinds of fabric besides cotton are used in "non-traditional" quilts...art quilts, crazy quilts, mixed media quilts, etc. Polyester blends, not so much, but velvets, silks, rayons, organzas, sheers, linens, lots of others, all are used for different types of quilts that you may not have considered.