The Foraging Wiffle Ball from Fundamentally Feline is a good beginner object. The many perforated holes increase scent attraction, it is round so it is easily rolled, and the cat can also see that there is food in the ball since it is not complete opaque. It is only available with onelarge hole for large kibble for obvious reasons, as it already has many small holes. Some cats hook their nails into the holes and learn to shake out the kibble!
Watch video below to see it in action!