Here’s a photo I found on Flickr. It’s from the Nation’s Attic (i.e., The Smithsonian). They have a great set of photos up there, so you should take a look.
The photograph below shows sheep grazing near the East Wing of the White House during World War I. Woodrow and Edith Wilson had the sheep roam the grounds so they could save money by not having to mow the grass. Also, the sheep’s wool was auctioned off to raise money for the Red Cross.
Sheep grazing at the White House (1919)
By the way, Woodrow Wilson House, up on S St. NW has a website and a blog that you should check out.