As the title says, the suggestion is to add a new object like the tiled background but with random images on it.
Each 'tile' will have a random sprite that you will select before.
The object could have a property where you could choose if the order should be random or not.
So to make it more clear..
let's say the 'random tile background object' you created have 32x32 dimension, you select 4 different images and in the layout you put the object and stretch it to 128x128, so it will be a total of 16 squares of 32x32, then the object will pick a random image from the selections you added before and add it to the tile, so each of it will have a random image on it.
It's good to make grass backgrounds, different types of grounds, etc.