I am in the middle of planning a memory quilt for a young woman who works at Joann. It will be made from her Nana's old house dresses. One of my first quilts was made from snippets of old clothing from my mother, father and their four daughters. It was beautiful. Way back then we didn't purchase fabric for quilts, we purchased it to make clothing. When the clothing was outgrown, it went into quilts. As for minding whether or not it is cotton, don't worry about that. Just be sure that the fabric is a similar weight. You will be carrying on a beautiful tradition in quilting and your children will have food on the table and beautiful quilts to warm their hearts.