I thought that maybe if you could do a humped dot, hand drawn like illustrated border, but just a nice 3d drawn shaded dot that might work well.
It would fit your drawn style tiles but not be so plain as the basic dot nor as intrusive as the illustrated stones.
The first 2 seem incongruous with your style.
It looks like you can do some variety with the illustrated style so maybe several illustrated dots. I'd like to see how that would look.