These are a couple cement block projects that can be used in your garden. The first is a raised bed made by just stacking the blocks on top of plastic to keep the weeds out. The good thing about this is it can be moved to another location as needed the next year. Sometimes you can get used cement blocks at recycled building supply places.
This next project is cement blocks stacked to form a outdoor bench with places to put plants and a little storage. The great thing about cement blocks is that they are very durable and last for years.