Not really knowing what I was doing, but knowing I was going to quilt when I retired; I would pick up small amt of fabrics I loved----3/8 yard minimum as it is more that a fat quarter or a yard or 2 if I felt it had potential to be used in a big way. I collected white and black prints because I knew I wanted to make a black and white with a little red one day. I ended up with a plastic bin full when I retired about a year and half ago. Now that has grown to 5 times or more of what I had going to thrift stores, fabric stores and things I have been given. I never turn down even a small piece of good cotton that is big enough to cut a small square from-------------------why because I prefer scrappy quilts.
Like some one said-----it just happens.