Canola, or Maybe Mustard

I have to admit, I can't really identify any of the plants that grow in the Palouse.  It's not like the Midwest where I grew up, corn and soybeans are pretty easy to tell apart.  I don't know wheat from lentils.  I initially assumed that this yellow flowering crop was canola, but I read online that canola and mustard are hard to tell apart to the untrained eye.  I also read that if you plant one of these crops in a field than you can never plant the other, because they cross to form a plant known as rapeseed, which is evidently a very unwelcome crop.  When I was in the Palouse last week I wandered through the Moscow Farmer's Market, and there was a vendor selling something I believe he called Canolina Oil, which was made from a mustard seed, but not the same as the mustard oil you would find at an ethnic grocery.  I tried some and thought it tasted delicious!  He had a lot of statistics and data worked up by the WSU campus to show all the health benefits, but I was a little skeptical on how well it would store given that he compared it against flax oil which oxidizes so quickly.  Anyway, that's my wishy-washy experience with this yellow flowering crop, whatever it is.  Not exactly my most definitive post!  :)