The VG Resource

Setting the mysteriously lit stones aside for the time being, I started working on my trees, I'm thinking I will make the dirt tiles beneath them have roots in them as well, and they definitely need trunks.

Personally, I think you could do without the rocks at all. Maybe one or two sprinkled about, but that's it.
The trees look alright, but a little more details, like a leaf outline or something might not go amiss. They also need to be varied. The lightest green shade also seems a tad too bright for me to look at.