As great as backgrounds are, they can get expensive. Think outside of the box! Here is a $2 solution, two black poster/presentation boards from the dollar store. I simply rubbed some white chalk over them and placed them behind my subject (my son, the stand-in!).
He was placed at the edge of the shade to allow the sun to still illuminate his face just enough to add a catch in his eyes and light his face evenly. This is very important when you are photographing in shade with nothing but available light. Placing your subject at the edge of the shade will also help reduce the blue light that shade provides.