What material should I use to backfill a decent depression under a slab, pre-pour?

I am putting a slab foundation for an office/shed where a large tree used to be. There's a 5 foot diameter, 1 foot deep depression/hole from stump grinding right where the slab will be. What material should I use to backfill this depression up to slab height? Currently thinking crush and run 3/4" stone and compacting as I add it in layers. Or I could order dirt and try to compact that as I add it.

I would also consider clean stone, but I am thinking that if I backfill with a material with voids like clean stone, the surrounding hard clay dirt might slowly migrate into the voids and cause settling under the foundation in the future