The high grass is where they go mid-day. The ground is still damp there, so that's where all the snails and slugs are (my flocks' favorite things to eat). It's also where the wild blackberries grow.
It helps that my lawn isn't really sod, like most lawns. It's just open space that gets mowed regularly. There's wild strawberries, clover, and other ground cover type plants growing all through it.
X2 - My girls eat their expensive organic food (littles start and grow and hens layer pellets) for about a minute then free range the back area the rest of the day. Same situation, not just lawn grass. What I've observed is that they nibble and walk, not just gobbling down loose grass.
BTW, congratulations marchick on your successful surgery. Best of luck on full recovery.