From Wiktionary, the free dictionary
From marrow + fat.
marrowfat (plural marrowfats)
- A large variety of pea that is often processed and sold in tins/cans.
1842, Charles Mason Hovey, Magazine of Horticulture, Botany, and All Useful Discoveries, page 319:Peas are scarce; good marrowfats are in better demand.
