If you tried preparing a handful of them the way you would, say, a lima or a fava, you'd be very disappointed. They must be soaked for weeks to remove the alkaloids, which are bitter and toxic, so one does wonder just how much experimenting it took to come up with something edible. (Incidentally, I have also wondered about the whoever was brave enough - or hungry enough - to first tackle an artichoke.)
My grandparents prepared lupini once or twice a year and we all loved them tossed with red wine vinegar, a little oil, and salt. (As per the standard Americanization of the Italian language, we called them "lupines" instead of "lupini" but on the other hand, contemporary Romans clip their ending vowels too.)
Here they are dried, lovely, a pale tan and roughly the size of a dime.
After a soak, boil, and simmer, the beans are soaked in water for weeks (from one to three) and the water is changed daily. I used a half gallon mason jar kept in the fridge. The soaking time varies based on the lupini; they need to be soaked and bravely tasted until they aren't bitter. When ready they have a firm bite, like edamame. Salt is added to the water when the are finished; some preparation directions call for soaking them in brine right from the start.
Now let's just stop here for a minute to recognize that these are beautiful, shall we? They are a lovely creamy yellow, now about the size of a nickle, and are just gorgeous. Okay, moving on.
The last task is to learn how to eat them - the outer covering is not eaten and is used to eject the lupini...no wait, that was when I was 10. We don't shoot them at each other any more, sorry. You can squeeze one edge to release the interior right into your mouth, or develop a technique of popping one in and doing some fancy maneuvering, sight unseen, in your mouth to separate the inedible from the delicious.
Here is a plate, ready to be served. Instead of red wine vinegar I splashed a little bit of balsamic (18 year; what else would they deserve?) and a sprinkle of salt. Lupini are nutritionally sound with a half cup containing about 150 calories, 14 grams of protein, 16 grams of fiber, and a fair amount of calcium and iron. Not a bad snack or addition to an antipasto plate.
You may find jars of ready-to-eat lupini in the Italian section of your market, but making your own will save you from the ridiculous amounts of salt they add. It is, however, an easy way to taste them.