All the chinese mustards are fast - too many types/names to mention, among them flat leaves, puckered leaves, feathered leaves, smooth leaves, even rough leaves more like radish but they still taste fresh and mustardy & grow very quick to a usable size for salad or wok. If you plant too many you will get the most delicious mustardy broccoli sprigs as they try to flower.
I use land cress as a tame weed/edible ground cover - totally bulletproof - it's brilliant raw and OK in stir fries if you run out of mustard - I chuck in lettuce leaves to compensate if I can - anything from tiny thinnings to the rough holey/torn leaves round the salad bit.
Cheers.