Latin name: Lathyrus tuberosus
Whilst garden peas are commonly grown both for edible pods and seeds, sweet peas are not edible however they are very ornamental. The tuberous kind is rare and it is perennial. The tuber stores the plants energy throughout the winter months under the soil protecting them from frost and helping the plant to grow rapidly when conditions are right in spring. This means the plants will keep coming back year after year without having to replant it.
Tubers are edible but with caution as some can be toxic depending on variety, for more info please see resource links below. The tuberous sweet pea is an excellent insectary, attracting many beneficial insects to your garden by providing food and habitat.
Resources:
https://pfaf.org/user/plant.aspx?LatinName=Lathyrus+tuberosus