Nominal rents are often called "peppercorn rents" because they often called for a peppercorn rather than a coin. Other things have been used, like a rose. Not always cheap. One Victorian rental called for a golden rose or golden pair of spurs.
Pondering what the -- ehem -- Good Folk would do. . . .
I think they would go for fantastical and absurd rents. Gold from a dragon's hoard, a branch from a given elder tree, a garland of specific flowers. . . .
One trusts that they would have magical precautions in place to ensure that the rent is what it looks like, not a piece of fairy gold. An Austen-inspired work set in Fairyland could come up with far more wild reasons than entails on the male line why the daughters of the family would be out in the cold when their father died.