If they are brand new and pecking eyes and beaks, I would not be too worried just yet. Baby chicks -like baby humans!- have to try everything out to see if its good to eat. Ours pecked eyes, beaks, and toes, for a week or so before they realized they were not nice shiny beetles or worms or whatever nature has hardwired their brains for. After a while they learn what's food.
Don't get too concerned unless they're pecking each other bare or drawing blood. But preventive measures are good: enough space (inceased as they grow), enough protein, and a red heat lamp.
And, I'd say 3 days is too young for grit and grass just yet...... you're just seeing normal baby behavior.