This is the floor in a basement kitchen of a house in NW Washington DC. As the story goes, at one time, the house belonged to a tile setter.
The tile setter brought home tiles left over from his jobs. He laid out patterns and combinations based on the tiles he happened to have on hand. He allowed himself to try things, without the yoke of rules, just to see what they looked like. He allowed his work to be imperfect. He let his children try their hands at his craft.