I am planning on building four raised beds in my backyard (2-3ft high; I have a lot of fill dirt to use up from a retaining wall project)). I was thinking about using landscape timbers for the walls (reinforced with rebar) but was concerned about the chemicals used to treat that wood. I don't know if I want that stuff getting into my food (or my dog). Related, I'm building a deck (adjacent to the future garden) and planned to use treated wood there as well. Any thoughts/other suggestions for each project?

You should be concern about the chemicals leaching into the soil. Always use untreated lumber when building your frame.

Pretty much what I was thinking. Thanks-