To grow where? Looks like grass is growing everywhere except on the wall.

As mentioned, I'd like to get grass to grow where the drainage stones are.

It looks like the grass stops a couple inches from the stone. Which means you don't have to run your trimmer there. Isn't that the ideal way?

I had the same problem. Looks like the area just behind the wall is back filled with crushed stone or quarry process for the sake of drainage. There is not enough soil there to sustain grass growth. What you have to do is dig a 6 inch wide and 4 inch deep shallow trench adjacent to the wall and fill with good quality top soil mixed with compost. Then compact it nicely with a hand tamper. Reseed with the same grass seed you have for the remaining lawn. In four weeks this problem will be history. I suggest you do this in the fall.