The earliest records of Brussel sprouts go back only as far as about 1800, and so are generally considered to be out of period. They are a biennial plant, and their strong flavour, typical of the brassica family, makes them highly unpopular.
On the other hand, they are exceptionally tasty if cooked the right way. I recommend steamed (or in the microwave) with chicken stock and saffron. Unlike a lot of other green vegetables they need to be cooked thoroughly so give them a proper blasting.