Answer: You are probably thinking of landscape timbers, often made of treated wood. These should be widely available at lumber yards and home & garden centers. They are usually connected using long galvanized nails or spikes; for short walls they are simply laid end to end and held in place with spikes. Take a close look at some of the examples in your neighborhood and you will see how to do it. Here are illustrated instructions, including how to make it level and straight. You may need to cut and paste the complete url into your browser to make it work correctly.
Good luck with your project!
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