Good idea for multiple reasons: equisetum (horsetail, snake grass, puzzlegrass) (grow zone grows so quickly and make even the newest newbie of a gardener feel accomplished and happy. equisetum can get out invasive and a container will control it.
How to: Grow a Salad Garden in a 2' x 2' box. Experiment: how many of these would I need to feed myself? Note: if making more than one, leave out the carrots and radishes. Replace some chard with kale. Add green onions.