Not from plants, but from micro-organisms and bacteria! Yum! Many of my foods are fortified with B12.

50% DV in my soy/almond milk, 40% in a single tbsp of nutritional yeast. I have a cup with cereal in the morning and a cup with dinner at night and I'm set. It's quite easy.

Personally, I'd rather get a shot than have to eat nutritional yeast.

Are you kidding? Nutritional yeast is delicious! You can put it on popcorn, include it in any recipe that calls for Parmesan (like risotto or cheesy pastas), use it for breading tofu, use it to make vegan mac n cheese. I love nutritional yeast...in case you can't tell. :) It just has an awful name.