We Recently bought 11 bags of these medium size white pebbles for the space under the Stairway in the entryway (we had tested smaller grey asian pebbles shown here).
I like the larger size pebbles and the white looks pretty nice and neutral. I was planning to make (or have B make) a piece of wood to paint white that could be inserted at the front to 'hold back' the pebbles and make them look enclosed. But R likes the way they are loose on the floor. He thinks they are more stylish this way. I'm not sure, but will leave it as is for now and see over time.