My present property (Portugal) had very few stones that big, so I have dealt with them by using a tpl box. A heavy lever underneath will help you roll them onto the box. Failing that, I have used a chain in the past (England, Scotland, Australia) to move boulders that weighed in excess of 2 tons UK - 2.25 US (on the basis that one cubic yard is approx 2 tons). Dragging them does sometimes gouge out a channel, but a chain is cheap compared with making something more sophisticated, and backfilling the gouge is usually not a problem. I have done other things, including making a proper 2 runner sledge, but that meant lifting the stones (or rather pushing them) up a ramp about 9" high to get them on the sledge. I have also pushed them with a tpl box, used a wire rope and winch; rolled them by hand (with a lever to help); and smashed them up into smaller sized pieces. Really big boulders are simply an interesting challenge in life. Millions of little ones are the real problem - but I have ways of fixing them too. Old McDonald.