We use crumbles but we feed out of a feeder. The only thing I put on the ground are meal worms, bread, veggies etc. Although Purina now has mash in pearls which I tried and liked but it sells out fast.
The problem I have is the nature of Chickens... lol
We feed them from feeders too. But they insist on kicking the feed out of the feeders into the dirt and then grind in more than they eat as they scratch. So pellets tend to survive this action better and they can still scratch them up later. :)