Hi , mailtophoo,
Perhaps you could post a bit more information on what you are looking for.
What format would be the most useful for you?
3DS, obj, poser?
Would the hill be in the forest or beside it?
What would be the scale of this model, i.e. 20 trees, 50 trees, 100 trees?
If youd care to supply that information then I'm sure I or someone else may have a few suggestions for you.
Thanks and happy searching
Maf.