"Unbleached parchment" refers to a type of paper that has not been treated or whitened with chemicals. It is a natural, light brown color. Full definition
Line 2 large and 2 small rimmed baking sheets with unbleached parchment paper and set them aside. (glutenfreeonashoestring.com)
Place another piece of unbleached parchment paper on top of the dough, and roll out into a rectangle that is about 1 inch thick. (glutenfreeonashoestring.com)
I don't like using plastic though and I don't have a glass container the right size, so I wrapped it in unbleached parchment paper, so that could be interesting too! (dishbydish.net)