From the Homemade Paper site
Bring the paper chase home to roost. Making your own paper is fun, easy, and a delightful project for the weekends. Note that this tutorial won't teach you to make printer-quality office paper (although you can recycle used office paper to make your own new paper) - it'll teach you to create pages of personalized pulp upon which to pen your powerful sentiments. Why? Homemade paper lends a distinctive personal touch to any project from greeting cards to a personal note or letter. And it's much easier than it sounds once you draw off a page or two.
Historically, the best papers in Europe were first made from a processed sheep, goat, or calf skin. Other parts of the world used woven vegetable fibers pounded together: the Egyptians used papyrus, a long coarse grass; and the cultures of China and Japan are known even today for producing very fine rice papers, made from the rice leaves or shoots. When the development of the printing press created a demand for paper, Europeans used old rags and recycled clothing, and eventually wood pulp from trees. Most paper products today, from newspapers to packing boxes, is made from wood pulp, a poor-quality fiber requiring glues and bleaches to be added. These additives, called sizing, account for the yellowing effect you see in old newspaper clippings. The quality of paper is largely based on the fibers used. Look around your home for attractive scraps you've been saving. Many different colors can be mixed, but bear in mind what the paper will be used for. Keep the colors relatively uniform and light in hue if it'll be used for writing. A small amount of glossy, bright paper can be added to otherwise bland fibers to give a speckled effect. Use scrap paper which contains a minimum of writing and printed ink on it. These could tint the paper unevenly, or worse, an unintended memo from the past could find its way back to the surface.