The yellow envelopes with the fabric in a ziploc bag works just fine and saves the buyer money on shipping.

Thanks every one. I'm going to go with the plastic bags and the brown envelopes. I've got a scale at work I can use to check weights to estimate the shipping amount when posting my sales. I'll still have to go to the post office to mail them, but I'll have a ballpark weight before hand :-D. Everything I'm planning to send so far is less than 13 oz., except for a couple of books that I'll use media rate for.