This link is a great resource for information on artists currently using "trash" to create beautiful works of art.
http://mentalfloss.com/article/13046/11-artists-doing-amazing-things-recycled-materials
Students are decorating Rhino sculptures while learning about and participating in Rhino conservation. So many levels of conservation here -- educating through participatory art as well as the final viewed art, teaching about conservation and using art as a medium to do so, as well as raising money for the cause. Great project!
http://taronga.org.au/media/media-release/thu-2013-12-19-1047/local-schools-wild-about-rhinos