I feel like I am the only one who lucked out and literally every swamp in my seed contains a bunch of Crypts... I cleared 7+ of them in one small swamp and filled a longship with iron scraps... not sure how much I'll even need if I ever get round to building anything with iron.

Funny enough the rarest materials for me are things like normal mushrooms and blueberries because I spend so little time roaming meadows and black forests now...