Raised garden beds do not have to be a huge construction project or expensive.
I have used cement blocks, bricks, stone, old doorways, and old boxes. When using any old found materials check for stains and paints that could be harmful to the soil.
Cement blocks warm up quickly so you can plant some of your crops earlier. You can also plant small plants in the holes in the blocks. I have planted herbs or flowers in the holes with much success. It looks nice and if you chose the right plants you can practice organic pest control.
If you take on a bigger project and build wood boxes for the raised beds just make sure you use unstained wood. It will have to be replaced in a few years but weatherized wood leaches chemicals into the soil and may affect your plants!
My one friend used old plates for an artistic garden art look. I have also seen bowling balls used.
One year I tried straw bales. It worked well but I had the expense of the bales. The advantage was I had great mulching material at the end of the season.
My favorite and most fun raised beds, really container gardening, is the use of bushel baskets. In the fall I collect bushel baskets at sales, farm stands or auctions. It doesn’t matter if they are a little beat up.
When planting time comes around I get the baskets up and fill them with the composted fresh soil I have made during the winter.
What I like about planting in bushel baskets is that I can chose theme baskets, move the baskets around or place them artistically around the yard or by the door as a mini garden.
The other big plus it that as much as I like gardening I do not like digging up root crops. Using the bushel baskets I can harvest root crops by placing a sheet or plastic near the basket and just turning it over and shaking out the contents. MY crop is harvested in seconds and I haul the used soil back to the compost pile to be re-conditioned!