What materials are the sheets made from? February 18, 2021 18:17 The Birch sheets are made from 100% organic cotton and include a 320 Thread Count with a sateen weave. Related articles What is a sateen weave? What are the different mattress sizes and dimensions? Can I return my Organic Pillow? How do I wash my Organic Pillow? How is my Birch Mattress shipped?