Toy collectors

My daughter is quite a collector of many things that she happens to come upon in her travels.  After our trip to the beach this summer, for example, we now have a beautiful collection of smooth stones in the garage.  These were collected from the beach on Lake Erie where the sand was mixed with myriad such stones.
These stones were of various shapes and sizes mixed with the sand - such that it would have been handy to have some kind of sieving tool at the time to help separate the stones from the sand.