I don't really mind the lighting that much, actually.
It's may be a little bit too flat, but on a typical overcast day you get similar lighting like this.
What you can try is reverting atmo to default and use a cloud layer to create the diffuse light.
You don't need a cloud fractal shader plugged into the cloud, just set the cloud coverage adjust to +1 and it will fill itself completely.
Then it's a matter of finding the height, depth and density which creates the light you're looking for.
I would start simple: 2000m altitude, 100m thick and density of 0.01.
If that completely obilterates shadows, then you need more light passing through, so reduce density (or thickness).
Logically, it also works the other way around.
So lighting is not so much of an issue for me, but the perfectly spherical flowering dandelions are a bit too perfect to my eye?