Need Smooth White Stone (or similar) in Mount Airy, MD

by CINDY
(Mount Airy, MD)

I have a serious drainage problem in my backyard, and after installing a drain and covering the yard every few weeks with new bales of straw, I have decided to cover the entire yard with stone. I have three very active Border Collies so grass is not an option (it was ruined a long time ago)-- neither are muddy dogs. I need to cover an area 25' x 50' with smooth white (or any nuetral color) stone. How much would it take to cover this size area and what is the cost?