Carl Sandburg loved being a plain-spoken dude. His goal was to speak directly to the people in a language that they could understand. As you may have noticed, our man Sandburg doesn't use long words or employ complex syntax. He's all about clarity and conciseness; just look at those last two lines of "Grass": "I am the grass. / Let me work" (10-11).
You can't get much clearer than that. And this is what Sandburg is known, and loved for. He tells it like it is, as directly as he can. Just check out "Chicago" and "Theme in Yellow" for more examples.