There was a famous Job ad in the "New Scientist" here in the UK some years ago for an "Edible Oil Technologist" but I am not sure how you would grow one, The leaves of Tomato and potato probably contain Atropine as they are both Nightshade family, Rhubarb leaves contain Oxalic acid which is toxic.
Sorrel is quite nice, when availabe, in salads adding a slightly acid tang and a salad of nasturtium leaves (be stingy and use very few so as not to overpower the other ingridients) young spinach,rocket and watercress in the right mix is Very Nice with a simple walnut oil ,Lime juice and a small amount of wine vinegar dressing