Most organ meat is underrated, but lamb's heart is particularly delicious. I've only ever been able to get it from lamb vendors at the farmers' market; it's so unpopular they usually just give it to me for free.
I was at a beach last week and couldn't help but pick up washed-up seaweed. But I have to admit, this was something I had to muster a little courage to eat. I've never picked up seaweed, cleaned it, and eaten it before.