Last fall we were able to salvage part of an old wood fence.  We love reclaimed wood in all its shapes and sizes and conditions.  The old fence posts were too short to be used as fence posts again, but were perfect for making garden boxes. 
In our main production garden we use wide rows and sheet mulching, but up in the yard area where I will be planting my flowers and medicinal herbs we are using garden boxes. The boxes will line the whole outer perimeter of the yard area.  Each box will have one type of either herb or flower, the large grouping will keep things neat and create a big visual impact.
 
Each box is simply two 4×4 posts stacked on top of each other and bolted together.

The bottom of each box is lined with several layers of card board to kill the weeds underneath.
 
On top of the cardboard goes several inches of dry leaves that we gathered from families in town.

My little helper, my star child, wetting down the leaves in the boxes.

 

On top of the leaves, we layered several of inches of well composted manure.  In a few weeks, after planting, several inches of chipped wood will go in the boxes and all around, helping to conserve water and build fertility.