We've been eating lots of baby carrots and parsnips lately, from a bag! Not a grocery store bag, mind you, but from one of these garden bags from Gardener's Supply Company. They sell them for potatoes, but I thought they'd also be great for other root veggies, and so far the carrots and parsnips have done great in them. The potatoes seem to be growing well too, but I'll have to do an update post when we actually harvest the potatoes.
We wanted a bit more growing space at the garden since our raised beds are pretty much stuffed to the gills with plants, and I saw these in the catalog. They're made of heavy-duty felt, and are supposed to last several years. Just fill them with nice sifted soil, water well, and plant your seeds. These would be great for small-space gardens like patios. So, even if you have cement for a "backyard", that's no excuse not to grow some food!