Which of these foods made me so gassy?

Last night I was on one heck of a fart-fest. Obviously something I ate for dinner had a bad effect on me but I can't figure out what. I ate a HUGE spinach salad - roughly 3 cups of fresh spinach, a cup of fresh Crimini mushrooms, a half cup of fresh cucumbers and dressed with oil and vinegar and a sprinkle of feta cheese. I then had 3 chicken legs that I barbecued (no skin) and a couple slices of flax bread. I drank water and a demitasse of espresso. None of this would've made me gassy. Or would it?