I see where you're going with the above ground thing. No peas are high carb & cals for the amount you get- 14.3g carbs & 78cals per 100g. I'd assume beans are the same. I know on SW all veg are free except peas, sweetcorn, pots etc as they're higher cab/cals than others.
I think the 790 sticky thread explains it much better than I ever could if not I have seen it recently & will try to hunt it out for you.