Here are some ideas on how to reuse your trash:
Turn old cards into postcards or gift tags. I bought a stencil kit years ago from Currant and I trace shapes onto the cards, then cut them out. I then punch holes into them and string them into the packages. I mostly use them at Christmas.
I just starting doing this this weekend. I took an old baby wipe container and put my plastic shopping bags in it. Make sure to fold them neatly so they pop out like wipes normally would when you remove them. ( I try not to have the plastic, but sometimes I forget my totes.)
Yogurt and cream cheese containers are excellent for making sandcastles or playing in the water. Savannah loves to pour water from one container to the next.
Aluminum cans can be used as noise makers for kids bikes. My son takes a can and runs over it with his bike. The can stays on the wheel and makes a motorcycle noise. He loves doing this!
Glass jars can be used to organize screws, nails, picture hangers. We have several baby food jars in the garage holding nails and screws. My mom used to to give us baby food jars to catch lightening bugs up north.
Use carpet remnants as doormats. A year ago, we had new carpet put in on our porch. We used a piece under the grill to catch spills. When we got new carpet in the house I put an extra piece under the shoe basket to keep the tile a little more clean.
These are just a few I could think of. Does anyone have other ideas? I love reducing our trash!