It depends on country and spec. If your tyres are RFT then the black shiny section on the left should be empty (it's for a jack and tyre slime). In the middle there is a cutout for your boot cover, it can go underneath diagonally.
My Australian 300 also came with a fold-out box, mesh strap divider/retainer, boot protector, breakdown warning triangle and 5 reflective jackets.
My Australian 300 also came with a fold-out box, mesh strap divider/retainer, boot protector, breakdown warning triangle and 5 reflective jackets.