It depends on why you want to give them scratch.My chickens won't eat corn or milo. Promise!!! What can I offer for scratch??
If you want something that chickens like to eat, that will make them run to you when you come in sight, you can put some normal chicken feed (crumbles or pellets) in a dish and add water. Chickens seem to love it, and get really excited when they see it coming. This can also be handy if you have let them out of the pen for some free ranging, and you want to lure them back in.
If you want something to encourage chickens to scratch around and get exercise, adding some fresh bedding can encourage them to scratch around. Or take a tool (maybe a shovel) and turn over some of the bedding or dirt they already have, so they can get to things underneath. Or you can give them various amounts of table scraps or vegetable and fruit scraps (peels, seeds, cores, and so forth: most of them are safe to offer chickens, and then the chickens can spend time eating the ones they want and scratching at the rest.)
A clump of sod or some material from a compost pile can also be fun for chickens to scratch in. Or a bay of hay or straw for them to pull apart.
If you specifically want a thing that is in dry little pieces and can be sprinkled on the ground, you could try other grains, or sunflower seeds, or dried mealworms, or cat food, or even pelleted chicken feed. I don't know what will appeal to your particular chickens, but you can probably find something if you experiment a little bit. (Note, many of those things are high in calories, especially fat, so large amounts can be bad for the health of the chickens. Small amounts are typically not an issue.)
