One of the best things about being crafty is the ideas for re-using things instead of throwing them away.
Some of my favorite things are:
Old torn jeans for potholders, purses and other tough sewn projects
Plastic milk jugs as structural inserts in embroidered beadwork and other kinds of embroidery
Plastic bags= PLARN!
Old deli containers work well as mini-greenhouses to start seedlings, a lot of them are #6 plastic which is shrinkable as well. Check the recycling number.
My son reuses plastic sushi trays as paint palettes and for small parts.
Cardboard packaging is used for lots of things in my house. It works for small templates for sewing projects, as structure for a purse, or as the armature for a sculpture. Combines with paper mache very well.
Newspapers can be woven to make situpons and baskets. Also one of the best things for paper mache. Gardening uses include seed tape or little seedling pots.
Shampoo bottles can be repurposed to make small watering cans, the tops can be cut off to hold brushes and other craft supplies, or they can be turned into little cases.
Wire coathangers can be used for book ends, blanket pins and all sorts of other things. DON'T use them for toasting marshmallows.
Right now I'm loving aluminum spangles made using punches from soda cans. A lot of hand punches work great with aluminum soda cans.
Popped bicycle innertubes work well cut open and in shorter lengths to help open jars. They also make a wonderful material for things like these rubber bracelets.