They save a bundle and it goes a long way. Look to nature - Nature crafts can be free if they are in your yard. If they are in your neighbor's yard or the park, better ask. Most people won't mind if you pick up their pinecones or acorns, but you might want to save flowers for drying from your own garden. Consider using plant and tree trimmings in your crafting too.
Evergreen branches make nice wreaths and twigs can be made into all kinds of things.
Sewing was also necessary unless you could afford a tailor. People often patched their old clothes, and there are many stories of recycling these fabrics by taking them apart at the seams and making smaller clothing for children. These fabrics could be turned into baby clothes when they got worn or outgrown. Remember, fabric was expensive, so it was reused. Take your hints from history and learn about how the craft you like originated.