Just in case you don't hear back from the photo's poster, here are some general equivalents to help you get started if you plan to add some rock landscaping or hardscaping elements to your yard.

The reddish-brown, smooth pebbles are likePremium Sunburst Pebbles

White pebbles could be Polynesian Pebbles, Ivory

Flagstone pieces look mixed, but you can see a large variety here: https://southwestboulder.com/t/categories/flagstone-and-ledgestone/

And there is one large boulder in the background.

Best of luck with your project, and feel free to give us a call if you'd like to ask any questions about using rock in a landscape. We're here to help. 760-461-3333.

They are river rocks. They come in different sizes and you should be able to find them in Home Depot, Walmart or a plant/garden nursery.