In the UK lupins are a garden flower. In the past, they were grown for cattle. But in France they eat edible lupins. It’s the white lupin that is eaten and only the seed.
Lupinus albus is a species of annual herb of the Fabaceae (bean) family, which is native to south-eastern Europe and western Asia. The Lupinus genus has nearly 600 species of herbaceous plants that are grown for their edible seeds or for their stately flower spikes.
Lupins are a legume, so they capture nitrogen and help feed both the plant and the soil. That’s good for your soil and the planet.
Don’t grow the normal garden varieties for eating as they have a high concentration of lupine which is a toxic alkaloid. Choose the varieties bred for eating. It is not thought they are available in the UK but they are available in France.