Working with reclaimed concrete (aka Urbanite)

I've been wanting to delineate the space in the front yard with a border of sorts. I want to build a dry-stack wall at the back side of the berm that is planted with various plants. I'm not particularly handy in this regard, and so I thought I'd do a test run on a smaller wall. A friend of mine has a pile of broken concrete at his farm, free for the taking so long as I load it. I went over there and picked through for pieces of the stuff I could imagine picking up more than once. I don't want to strain my old herniated disc in the course of this experiment. So my pieces were 8-15 lbs.

I've been thinking about this project for a while, but I hadn't really done much planning, other than knowing I'd cover the grass with cardboard, cover the cardboard with the concrete, and fill in the space with soil and plants. Measuring did not occur - this is only a test.

Space before the wall. Grass invades bed, space is not clearly delineated.

Rough draft.

Close up with herbs planted in between slabs. They will act as mortar once their roots grow.

 I've built this thing and filled it in with soil and plants, and I'll take a look at how it goes for a while. When I think about it, and observe it, for a good while, I'll think about tackling the wall that will be about five times longer. I planted culinary herbs, since the bed is near the kitchen, I moved in some irises that were out of the spotlight, I planted a couple of echinaceas that my neighbor brought over. Good thing too, since a gopher just made a snack of one of the existing echinaceas in that general vicinity.

I've since dug a trench in front of the wall, and turned the sod over, sowed it with daikon, wheat, and fava beans (my favorite fall mix). I've also put in some cuttings of rosemary and some salvias in front of the wall. This will all help to build soil and to create a place for many of those beneficial insects and pleasant hummingbirds I welcome into my yard.