I first heard of Hugelkultur on the podcast A Way to Garden. The link takes you to that episode's shownotes, which also list the basic steps to creating a Hugelkultur bed. (I'm capitalizing the word because it's obviously German. This idea has apparently been around for hundreds of years.)
The basic idea is to create a new bed with sheet composting—except that your base layer is WOOD. Twigs, branches, even logs. Just like in a forest.
Here's a website with some terrific diagrams.
The flaw in the forest bed logic, of course, is that you don't go trying to grow vegetables in a forest—it's a different type of plants that flourish in forest undergrowth. Nevertheless, they talked about how the sticks foster pockets of air in the bed. Plus, my main problem with starting any raised beds was trying to fill them. That could get expensive fast, if I had to purchase the soil. Wood in the bottom means perhaps not having to come up with as much soil. It's sort of the same principle as putting rocks in the bottom of a planter—and also would serve the same purpose of helping drainage.
I had no worries about where to get the wood. I live in a neighborhood full of mature trees, including the maple in my back yard. They're always shedding at least twigs, and often larger pieces. As soon as I heard this podcast, I stopped putting the fallen maple bits on the curb for pickup. I just kept adding more in the old cracked trash can I keep for the purpose.
When Gardener's Supply Company put their basic Grow Beds on sale after the spring planting season was done, I ordered one 3'x6' kit. It has 10" high walls. I figured that would make it easier for me, plus my neighbors would be less likely to object if my pile of sticks were contained.
My yard is configured with a triangular bed in the SW corner, which gets the most sun, and 2-foot-wide beds all around the rest of the perimeter. (These were already in place when I moved in, and mostly filled with perennial flowers.) This new bed is my first step toward filling the sunny third of the yard with vegetable beds that START organic. (I'm having to regenerate the existing beds, which were addicted to chemicals before I moved in.)
I set up the raised bed a mower's width away from the perimeter bed to the south and the corner bed to the west. Underneath it I mowed very short and then laid out the boxes that the raised bed came in, to block the growth of grass and weeds. Then I dumped in my collected twigs and branches.
Oops... not quite enough.
But that was July. I still had plenty of time to collect more wood. I started watching for downed branches around the neighborhood while walking the dog. I chose the largest ones, since I could only use one hand to get them home. I got a real prize one day after a storm—a piece of tree LIMB over 5 feet long and about 6" thick.
As of today, I've pretty much got all the wood I need in there. I still continue to add anything that falls off the maple, plus anything I see during walks that's irresistible. But as soon as I get over the bronchitis I'm fighting right now, I'm on to the next step.
What'll that be? Leaf mould. Stay tuned.