You have until Oct. 31 to submit your art and interactive installation proposals for LAWN NATION: Art & Science of the American Lawn, an exhibition planned for May 2008 by the Notebaert Nature Museum. The in-house exhibit will explore America's love-hate relationship with grass through works of art, installations and special events. Here's a suggestion: An installation featuring sprinklers that actually water the grass, not the sidewalk or the heads and feet of passersby.