Ducken, my wife and I have picked up about 20 loads of flat rock up to 3 or 4 feet across near detriot lake. Go to the ranger station there and pay $10 for a 30 day permit. It will allow you to harvest up to ten loads of rock. The quarry you want to go to is Dead Horse. Bring a heavy breaker bar. You can slam it into the large boulders and sluff off huge 2-3 inch slabs and then load them into your truck. It is a lot of fun. There are plenty of huckleberries and grouse up there as well.