Most of the little creeks have gravel and sand alongside them. Gravel mines can be seen on google earth all along the creeks. Screeners work there most of the year building up some gravel mountains. I've got a little creek on the quarter across the road where I've hauled a lot of fill  from. Its everything from fine beach sand to rocks as big as a hall closet. Pit run is pretty rocky for road use so when my driveway needed gravel last year I just called the local gravel guys to haul a couple of loads of decent gravel. That way I didn't have to spend a day picking rocks off my driveway.