Plastic bags, including supermarket-carry-home-bags, can be cut so that they turn into loops of plastic. If you cut them wide, they can support even a heavy leaner without cutting into the stem or hurting the skin.
Then there's the really old, classic "pea brush". If you have woody twigs falling in your yard, or you trim them from trees and bushes, save them for pole beans and tall peas. Especially prize the "Y"s and tripod twigs. You can push them into the ground around the peas or beans, forming a jungle gym that the vines will climb.
P.S. I never like the way that unsupported "bush" peas flop and draggle on the soil surface. They don't look happy, either. If I give them even a single string or branch to cling to, they stand up straighter, catch more light, stay cleaner, and are easier to pick. They seem happier, also!
