Aka Deadstock fabric - excess and leftover fabric from other brands, who buy more than they might need. These are fabrics that get lost in a huge warehouse and eventually end up in landfills. The thought of that really ruffles our feathers, so we treasure hunt to find the best ones and cut as many pieces as we can out of them. Once a fabric is gone, we may never find it again. It's the equivalent to finding a vintage gem - how often do you come upon an exact copy of your favorite piece?
P.S. Rayon is made from wood pulp, a naturally-occurring, cellulose-based raw material making it biodegradable, so that's cool too.