arugula
Arugula, or rocket if you are from the UK is a popular salad green. It has a peppery flavor and aroma. By the way, this green is original to Italy where it is called rucola.
You can use arugula in salads, sandwiches, or even toss it in with pasta at the very end, right before you are ready to serve. It adds a nice texture. By the way you can put it on pizza as well.