I use either pine shavings or alternately untreated wood pellets. The pellets are less dusty, but don't smell nearly as nice. I have never covered my shavings and have yet to have any of the thousands of chicks I have raised eat them. They do peck at them, but I have never seen them ingest them.
Occasionally, I have used cedar. Used to hear about how bad they were and then spoke with an octogenarian, third generation chicken keeper, who is a well known poultry judge. They told me they had used cedar their whole lives with no problems. Sometimes I think someone just formulates a theoretical idea and then writes it down in a guide somewhere and next thing you know, people are quoting it like it's the gospel without having the benefit of trying it out....
Another couple tips I find nifty for brooding-- using ceramic heat emitters so they can have a natural night time; and when they are 1.5-2 weeks old, putting a grassy divot in their brooder (I use those large sheep stock tanks- 4'x2'x4'). The ceramic heat emitters function like a heat bulb, and while pricey, are guaranteed by their manufacturer for five years. Mine have lasted well beyond this and have saved me a lot of money in the long run as I find those red heat bulbs barely make it through a season. They are available wherever reptile supplies are sold. The grassy divot give the chicks a natural playground; greens to nibble and dirt to scratch around in. I find it keeps the wee ones entertained and helps with their health to get introduced to the soil they will be living on when older.