You can, but fresh is going to work better and taste better in my opinion. I haven't tested the recipe with frozen green beans, but that would be my next choice if you can't find fresh ones. I would put the beans in frozen at the same time as the recipe says to add the fresh beans and follow all the same instructions. As far as canned green beans go, I would drain the liquid and add them in AFTER the pressure cook time and just warm them through. They are fully cooked already and I'm not sure how well they would fair being pressure cooked.