I see a pattern that I love and either purchase it, make a note as to what magazine I found it in, go online and download it. When I go to Jo-Ann's to pick up thread or some other small item I always feel the need to check the fabric. Big mistake, of course there will always be one that calls out. As to the original question, the fabric is purchased with something or someone very definite in mind. Then I find the pattern that suits the fabric.