Talfadan refuses to leave his farm until after his grazing sheep are brought back so that he may lead them to safety.
'All right, I hate to say this but you've convinced me that I should head over to the White City. There's one last thing that needs to be done though.
'My sheep are out grazing and I can't leave them here. I would never forgive myself if some ruffians got to them!
'Will you go get my sheep and bring them back to the farm so that I may herd them to City?'
Sheep can be found grazing in the south-western corner of Pelennor Fields.
You should find and return the sheep to Talfadan.
Sheep and Morgul Scouts can be found grazing in the south-western corner of Pelennor Fields.
You should find and return the sheep to Talfadan as well as defeat the Morgul Scouts.
Turgon can be found at the South-gate of the Rammas.
You should speak with Turgon.