1. In a bowl mix together the oils, vinegar and seasonings. Pour over the mushrooms. Cover and marinate for 1 hour (do not leave in the marinate for more than 2 hours or the mushrooms will turn dark).
2. Clean, wash and pat dry spinach and lettuce. Cut in bite pieces. Mix with the mushrooms and add the dressing, stirring softly. Decorate with chopped parsley.