Pole Beans, Bush Beans, Zuchinni, Lettuce, Scallions, Tomatoes, Peppers....
They all do pretty good in single rows like you have.
When I had single rows like that I ended up putting permanent plants in like Rhubarb, Horse Radish, Red Currants and Elderberrys.
I like home made concoctions like Rhubarb Custard or Strawberry/Rhubarb Pies, Currant Jelly and Elderberry Wine.
Right now I can't wait for the end of April to get here so I can pick some Rhubarb.