These are fabrics specifically designed for garment making industry (not that they can't be used to make other thing, or that you can't make garments out of other types of fabrics). Many of these were created to the specifications of fashion designers, and hence may be very high in quality. They become available to us when excess fabric is left over after production of a designers line. Often referred to as "deadstock" fabrics, these are an environmentally friendly choice in that they save unused fabrics from being wasted and ending up in landfills.
Merchant & Mills, European Laundered Linen, "Bijou Wes" Tiny Pink and Mustard Check, 1/2 yard