shorty wrote:I don't know if I will be able to by the food in a small quantity.
You can buy food in any quantity, be it a single tomato, a shot of wheatgrass or a muffin. You can not only assemble a picnic on your own, but there are vendors who will prepare food for you to consume there (crepes, sandwiches). Just be forewarned that it's an "upscale" farmer's market with very good quality products at pretty high prices.
Here's a list of "usual" vendors:
http://www.chicagogreencitymarket.org/f ... p?type=allAlthough most usually show up, sometimes the one you want won't be there.