They aren't really big, as said, but still...
1: Some of the grass clumps float, adding nasty shadowy ridges under them. If you'd use rotation with the terrain, that would be better, I guess. I tend to make my grasses now that the stems are more extended undergrouind, especially on the verges of a patch. A little minus offset of the object also helps sometimes (unless it's to shallow and ducks completely).
2. Tiny unrendered part so it seems, due to extreme displacement and not enough tolerance. Just a bit of cloning would do.
3. I think I would extend the grass (procedurally or not) further into the landscape. On the left it has a very abrupt end, but that may also be because of a ridge.