You can totally feed your Food Grounds to your flock!
Just remember that your grounds are a mix of the food you couldn’t or didn’t eat and best used as a feed ingredient, not a full feed. You’ll likely want to include other feed in the chickens’ diet too. There are some scraps that can be harmful and potentially toxic to chickens, like avocado pits and onions, so you’ll want to be careful adding those types of scraps, just as you might not feed them directly to your chickens if you didn’t have the Mill.