Cahokia is the site of a Native American city that existed between 1050 and 1350 CE in Illinois, right across from modern-day St. Louis.

They dug their houses into the ground, which helped with insulation! So they had a house in a mound by the river.

There is a small blurb about it on Cahokia’s wikipedia article:

Cahokian domestic structures were generally of pole-and-thatch construction and followed rectangular footprints. Wall trenches were often used instead of posts for building construction.

I also have a book about Cahokia that describes it:

In these Indian houses, wall posts are set vertically into the earth. Floors are dug below the ground surface to keep out the summer heat and the winter cold, so people have to step down to enter through the small doorways. Earth is heaped up against these semisubterranean houses’ exterior walls, and the gabled roofs, covered with thick golden thatch, are brought close to the ground.

From Cahokia: Ancient America’s Great City on the Mississippi by Timothy R. Pauketat. Publisher link