Not super common, but the easiest most versatile plant I grow is Seombadi/Korean Celery/Dystaenia takesimana. This stuff is amazing. Zone 6b temperate NE in the US- it is a perennial and overwinters without any difficulty, can brush snow aside and harvest lightly even in Feb or March. It's now started to self seed and I'm happily giving seedlings away the my unsuspecting neighbors. Mild flavor, depending of the age of the shoot and leaf it can be used in salads, stir fry, or soups. Also while the groundhog and rabbits eat it, they don't decimate it like other plants (any brassicas, or squash varieties I try to grow that's not fully fenced). Attached is a pic from early April this year after a very hard winter and not much else is green yet.