Egg carton- This is a great idea of truffles or jewelry!
Fabric- You can incorporate your take on furoshiki by using a T-shirt or scarf
Yarn– You can use miscellaneous yarn pieces to fashion gift topper pom poms (tutorial), or you can get some doilies from your local thrift shop for another topper idea
Toilet paper rolls
Paper shopping bags- The example below uses the outside of the bag but I would turn them inside out for a plain canvas. Once you do that you can decorate to your heart’s content! Here are some ideas: rapping paper, paint, stamps, bows, cut outs, washi tape
Cereal box gift toppers
Reusable grocery/shopping bags