These are soap nuts:
The term "natural" gets thrown around a lot these days, but I'm excited about using something that I can see for myself is from nature. Soap nuts (also called soap berries) grow on trees in temperate and tropical regions of the world. This particular brand I bought, Maggie's, imports soap nuts from Indonesia.
So, all you have to do is put five soap nuts in the cloth bag provided, and throw it in with your laundry. That's it. Then you re-use those 5 soap nuts for 5 loads of laundry.
Oh, and after you're done? Just toss the soap nuts into your compost. I love that! I don't have a verdict yet on how well they clean, but I'll let you know once I've done a few more loads of laundry!