Yes you can use materials found in the trash to recycle into artwork. Here is an assignment that was shared with my art class.

Objective: Use found materials to create a 3D form

Look for interesting materials that can be combined into a dynamic sculptural forms. Artists have been recycling before it became popular.

Use everyday objects that have been used for another function. Now alter the use of the objects into a new visual context. The intent is to cause the viewer to see what you have made in a fresh new way.
Look at what Pablo Picasso did with sheet metal and wire in the work called the “Guitar” Below.

Check the following links of found object artists Kris Borchardt, Bruce Gray , folk artist Jim Shores and New Jersey artist Willie Cole.

Materials: Use only materials that you find  and not purchased. This project should take less than 10 hours.