Organic cotton tends to be the best option for your baby-receiving blankets. It can come in various forms and thicknesses, including muslin and flannel. Cotton is a natural and breathable fabric that is soft and gentle on a baby's delicate skin. Muslin is lightweight and breathable, making it a great option for warmer weather. Flannel is a warm and cozy fabric that is perfect for cooler temperatures. Bamboo is another relatively good option that tends to be cooler and lightweight, but whether or not it's truly "non-toxic" and "eco-friendly" depends on how it's produced. Additionally, remember that the dyes and finishes matter, too.