Looks like you've run into Sheffield the Sheepherder. Sheffield travels the many paths of the Kimberroo mountains. Other travelers have tried, most ended up missing or needed rescue. The mountains hold many plants and vegetation that cannot be found anywhere else. Maybe if you're nice to Sheffield, he will bring some of those plants back to you.
Items you can gain from this quest:

Elderberry

Dogwood

Crabapple

Blackberry

Bearberry

Aster

Alfalfa

Thimbleberry

Soapberry

Tayberry

Jostaberry

Loganberry

Lingonberry

Gooseberry

Choke Cherry

Black Twinberry

Indian Plum

Salal

Salmonberry

Snow Berry

Bamboo

Black-Eyed Susans

Crimson Tigerberry