Two years ago, I got a couple of bookcases from work, knocked the backs off and made raised beds out of them. Overall, they have been a good choice for this project. Last year I reinforced the corners with wood screws, but missed on one corner, and that corner let go over the winter. Not a lot, but it needed to be shored up.
I am a big fan of rebar, metal poles 3/8" or 1/2" in diameter. I bought a bunch of 3' pieces to shore up the two beds. For the loose corner, I dug the soil away and then, in a move that must have looked less than poised, pushed on the side of the raised bed with my foot, and pounded two pieces of rebar to hold the vertical side of the raised bed in place. It worked fine, and I reinforced the other sides as well.
Last year I bought some landscape timbers to use for edging, and ended up not using them, so they sat for a while, and then I thought I'd make a third raised bed from them.
This is from last July, but shows one layer of timbers. I've got enough timbers for three layers, and I started putting that together yesterday. The weather was so nice that I was surprised to find the mulch still frozen on the lower left corner such that I couldn't really move it all yet.
It's going to be a nice sized bed, and I've been thinking about what I should put there. I'm OK with narrowing the kinds of stuff I plant. I'm growing all the vegetables that Mr W and I will eat in the two existing beds, and I'm more than OK with buying veggies at the farmers market to supplement. We both love fresh fruit in the summertime, though, so I'm going to plant this third bed with strawberries. I'll also ramp up our cantaloupe plantings. You can see the raspberry patch between the two beds that's been nice to have, although not much of the fruit makes it into the house because we eat it as it's picked. The dog really likes raspberries too.
And since I like roses, I'm going to stick a new, to be determined variety of rose bush in there as well. I've got a bunch of compost that I can put on the bottom of this bed, and was talking to friends at the dog park who mentioned a couple of people with trucks that might help with soil hauling.
I'm going to get the deck built off the living room (so help me), and will have it built so it's sturdy enough to support a grape vine for shade. With the apple tree, that'll be five kinds of fruit we'll grow ourselves in this so-so fruit growing part of the world. Now, if I could find the space for a cherry tree....