Since I am a quilter people give me fabric. Some is so thin you can read through it. I use those for foundation for scrappy quilts instead of using paper to keep it stable. You don't have to take it out later. Sometimes I use some of those odd fabrics for pieced backs. Depending on how you do it it can make the quilt reversible.
Sometimes you just have a fabric that are a "what was I thinking" fabric. If you can't think of how to use it, ask a quilting friend for ideas, trade it, sell it, donate it. It will help get rid of the guilt and give you space.