I live in the Midwest USA and I'm making plans for a rock garden inspired by one in Japan. I would probably need something tolerant to winter temperatures and hot summers, along with a mostly sunny lawn (I've got 2 trees packed into the corner of my backyard, one large birch, and one maple that's ~13 feet tall), just a generally hardy species that can tolerate the climate of the Midwest.
What's the best species for this garden project?