I use to throw away the left overs from quilts. Then I someone wrote how the scraps add up and the cost is there. So i've started saving anything more than what I call a snibble. I've done a quick whip stitch to hold them, but have also found if the quilting is fairly close, that isn't needed. I've also started to do some quilts in the QAYG method which is perfect for using up those 15" width scraps. Everyone above is correct in that you really cannot tell where they are joined after the quilt is quilted and washed. I try not to think of all the batting I use to just toss. Shudder....