There used to be some at 3DPlants, but I think that site is gone now.  They were older models anyway, probably not up to today's standards.

There might be something among XFrog's free plants you can use.  There's ginger, though it's the plant, not the root:

http://xfrog.com/category/samples.html

If have Vue, there are several products at Cornucopia3D, including this free Italian kitchen herbs pack:

http://www.cornucopia3d.com/purchase.php?item_id=2662