I just wanted to put in my two-cents worth. I was born and raised on Oahu as was my mother and father. I remember my mom telling me once that they (her family anyway) became dependent on canned foods such as spam, canned corned beef, vienna sausage during the war with Japan when fresh food and other dry goods were in very short supply. I have very fond memories of my mom packing me a bento lunch with two musubi (rice balls wrapped in nori), scrambled shoyu eggs and fried spam, vienna sausage or shoyu hot dog. Even though I know it's really unhealthy, the smell or occasional taste of it brings back really fond memories of childhood. I must also say that the best way to eat a bento is to spend the whole day at the beach under the hot sun in the salty ocean water, then eat your bento with an ice-cold soda pop! It's the BEST!
