Ok, the goal was to do this without having to make a trip to the hardware store for supplies (but I might go to the local nursery/landscape supply place and get some really good dirt).
So I started by digging out all of my left over redwood fencing supplies from a recent project and sorting them out:
That long piece is 8 feet tall, 12 inches wide, and has a split. The other two planks are 5 feet long, so I decided to basically cut a foot off the taller one and then cut that in half for the sides. They'll be about 40 inches. And I'll just leave the front and back pieces their original 5 feet. Then I got to work building a really basic frame:
... which turned out okay... I used scrap 2x2's and an old 2x3 to act as corner supports and left the pieces long so they could sit in holes I dug in order to keep the box/frame/bed from moving too much. I used some galvanized deck screws to put it all together since I had them on hand and they would do better job of pulling in the cupping of the planks. Those had been in my garage rafters for a couple of years and they were badly cupped.
Here's the leftover from my leftovers pile:
And the finished box in place. I swear it's level. You'll just have to take my word on it though... :) I haven't filled it with dirt yet, and as you can see the whole place is a mess, so I'll have to go out there and do some cleaning up.
While I was digging around, I found lots of tunnels. I don't know what made the tunnels but a neighbor claims to have seen moles (or was it voles?) in their yard recently. That's something we haven't had to deal with before in the 12 years we've lived here. Maybe I should put some metal mesh at the bottom of the box...