I don't waste any batting! I use the larger pieces to make baby quilts. I don't stitch them together, instead, I place the largest piece of batting on the quilt back then add other pieces overlapping about 1/2 inch until the backing is completely covered. Carefully add the quilt top and pin. Here's the trick--pin on both sides of the batting "seam" and make sure to quilt heavily. Baby quilts need plenty of quilting if they are going to be dragged around.
Medium sized pieces are used for small quilting projects: purses, table runners, pot holders, etc.
Small pieces of batting are chopped up into about 4 inch pieces. I then pull them apart to make smaller pieces. (They're fluffier this way.) I toss them into a bag and use it for stuffing toy animals for the grandkids and as gifts.
One more idea for stuffed animals is to put a small rock or bb's into a medicine bottle with a child-proof cap and add it to the fullest part of the toy for a rattle.