As far as we know there is little
that's economical to bring back to earth. There are quite possibly enormous iron and nickel reserves from meteor impacts (e.g. [1]). Mining them for use on earth isn't that interesting, but if you want to build large structures in space (or on the moon) having metal that far out of earth's gravity well is pretty valuable.
And then there are the unknown unknowns. We spend a lot of time prospecting earth, and haven't spent all that much prospecting the moon. This will be much easier with boots on the ground. And while the moon's lack of geological activity means it isn't good at concentrating resources, it also means remains from impact events remain much more reachable and concentrated than on earth.
1: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL08...