Hi cnelson. Welcome to NGA!
You might like building small raised beds that are a lot like large boxes. If the raised bed sits in impermeable clay, it is exactly like a big box! I use concrete paving stones stood on end for walls. The 12" x 12" x 1" are the sturdiest, but 8" x 16" x 3/4" pavers let you chose 8" walls or 16" walls.
However, in hot country, boxes and raised beds let the soil heat up very quickly when the sun hits them. Paint them white or surround them with something white that lets air circulate while shading the root zone. And if loosely leaning concrete pavers let the soil dry out too fast, line the walls or at least the corners with plastic (leaving some drainage holes or slits).
Skip past all the "trenching" photos here to see a variety of "concrete paving stone beds". Page down 2/3rds of the way.
http://garden.org/thread/view_...
After I put that post together, I realized that I must have 10% mole ancestry.
