Natto: a traditional Japanese food made from soybeans fermented with Bacillus subtilis. - Wiki
Pictured above is the Natto handroll served at Noshi Sushi on Beverly Blvd. in Los Angeles. I absolutely love natto but you probably won't hear that from many people. The natto beans which are fermented smell like stinky socks and may even leave a similar after-taste in your mouth although in my opinion eating natto really isn't half as bad as it smells, instead the taste is a tad bitter, pungent, nutty with slight saltiness and the texture slimy and gooey, which is most probably the reason for it's unpopularity in Japanese restaurants, natto is not even listed on the Noshi Sushi menu although the restaurant does have it in stock to serve, simply ask them.
I often find that most Japanese sushi restaurants do not have natto and so when I do find a Japanese restaurant that does serve it it's a reason for me to get very excited! I had two in one night!
Taste, smell and texture aside natto is very nutritious and has many valuable healthy aspects.
Though I would never ask anyone to eat natto, only because I'm sure pretty sure what their reaction would be, if you're adventurous and want to risk trying something new (and for $2.50 a handroll @Noshi Sushi I don't see why not) I would say give it a try. And to be honest the chances you'll like it is close to zero but it would be a rather interesting and unique experience I'm sure. Natto is one of the oldest food in Japan dating back to Ancient Japan, in this way you can't get any closer to Japanese history.