Lettuce
Lettuce brings sweetness, and that all important crunch to salads. It's a great foil for the fiery taste of mizuna and rocket. Tear/chop the leaves coarsely and mix with any of the dressings listed for salad leaves.
Leafy herbs are a great addition to lettuce or green salads. Pick whatever you have available - parsley, chervil, coriander, chives. And of course other green veg fits nicely too - shavings of fennel cut with a mandolin, sugar snap peas, cucumber. And don't forget the growing tips of your broad beans!
Lettuce also mixes wonderfully with nuts. Toast the nuts and in an ideal world make the dressing using the nut oil - hazelnut, walnut etc. A fantastic side dish or accompaniment to any cheese.