I love to garden, and and easy way for us to have all the fresh veggies on hand is to have raised beds in my back yard. We took some old fence boards from when we replaced out fence, and turned them into planters.
Start with some old fence board, even the 4x4 posts. People in your neighborhood are always replaceing fences, so ask them for the boards, or if you are going to replace your fence, keep them for future projects!!
Cut a slit into the 4 x4 at a right angel to each other, you need to do this to 4 board to make a square or rectangle bed. Slide 4 fence boards into the cut. This makes each bed about 2 feet tall, but you can make them as tall or as short as you want.
Here is a square version we made, and also added a top "cover" to it to finshin it off and make it look pretty, the cover also let you rest your tools and supplies as a little ledge when working in the beds.
Here is a video tour of the planters we set up 4 years ago.