Here are some blocks I've done with crumbs. As you can see, some of my "crumbs" are pretty big. Just depends on how patient I feel on a given day.
The square in a square blocks are actually done crazy quilt style, on a foundation of ugly fabric, but you could do it with crumbs.
The blue block was made after I made a miniature sampler with blue and white, and wanted to get rid of most of the small bits that were leftover.