The river bank lined with weeping willow trees. In the story, the grass is much longer.
Traditional English cornfields adorned with poppies. Such sights are sadly rare nowadays but were commonplace before the Second World War.
http://www.stats.ox.ac.uk/~ripley/Photos/Vercors2004/d29v0426.html
shrewsbury.gov.uk/.../Gallery/outoftown.htm
The Yorkshire Dales. I imagine the Kingdom of Arnor to be rather like the Yorkshire Moors and Dales.
www.travelwatch.org.uk/.../yorkshire_dal