A group called "Chicago the Beautiful" is producing thousands of of free art to distribute for the public. The name of the project is called "The Free Art Machine." There are plenty of ways to participate.
1) Be a part of their kickstarter
They reached their $8,000 goal with $22,074 pledged via kickstarter. But you can feel free to donate to their campaign and get some art mailed to you.
2) Submit photos to be in the project
Or you can upload your own photos to be part of the project. When there is a public art experiment in Chicago, I very much want to participate, so I submitted nine of my recent photos to be in The Free Art Machine.