dirt

I'm sorry if this has been covered already (and if so please just post the link to the subject), but I fail at searching. We grow our own wheat, and I find it very tedious to hand "rummage" through the wheat berries to cull out the stones and dirt. Is there something clever, without using water or buying another piece of expensive equipment, that I can do to make this job a little easier?

Thank you!

Sheri