Due to settling it is incredibly difficult to tell what was loaded. I've loaded compost into a 5 yard trailer with a bit of a centre heap and just driving it 5 miles it had settled about 4 or 5 inches. If you can watch them load and know the volume of the bucket you can get an idea of what you are getting. Other than that you're pretty well at the mercy of the supplier.

Lloyd

Finding out how big the truck was that delivered it would give you an idea also.

If they are dumping in a nice pile, you can probably estimate the volume with a measuring tape and a little geometry. I like the truck size idea better though.

Because of the entrained air in the soil when it is loaded there will always be settling. Unless your states department the regulates weights and measures certifies how the landscape company loads this bilk material you may not get the exact amount you ordered although it will be fairly close. Most often, in my experience, reputable landscape companies will load a bit more rather then a bit less.