“Shroud usually refers to an item, such as a cloth, that covers or protects some other object. The term is most often used in reference to burial sheets, mound shroud, grave clothes, winding-cloths or winding-sheets, such as the famous Shroud of Turin or Tachrichim (burial shrouds) that Jews are dressed in for burial.” View on Wikipedia
There is no mystery here. You can purchase a shroud from eBay, Amazon, or a host of religious and non-religious providers you can find on the internet. If you have a quilt with historical significance to your family, or a stunning sari you bought on vacation, you can personalize your shroud. A simple piece of linen or silk painted by the artists in your circle (amateurs and professionals) can do the job as well. For a Green Burial, you want to use a natural fiber with natural and non-toxic inks.