After you've been quilting a while, you usually end up with some odd shaped scraps of batting, that aren't really big enough to do anything with. What you can do, if you want to use things up, is you can piece the batting.
The important thing to remember, when you're piece batting, is you don't want to overlap it, or you don't make a seam. You want to let them together. You don't want any extra lumps, or bulges. You don't want to layer them. Just nice, and tightly together.
Set your machine to a zigzag stitch. Put the presser foot down, and just make sure your stitches are falling on either side of your seam line.
So, there you have a nice piece of seamed batting.
There's another way you can piece batting, that doesn't involved the sewing machine. There's a wonderful new product, Heat Press Batting, and, all you do is, put your two pieces of batting together, once again, but it together. Cut a piece of the tape, the size that you need for your batting, and just press.
This is a great fix if, for example, you've done what I've done, is cut your batting too short, and you get to the end, and you find out you just don't have enough. Well, you can just stick your quilt on the ironing board, and fix it that way. That's the quickest, easiest fix ever.
So, yes, there is a way you can re-use your batting scraps. Heat activated tape, or zigzag sewing on the machine. Either way, it's a great way to reuse your scraps.