He is called the Grasshopper Mouse.
"The Burgess Animal Book for Children" by Thornton W. Burgess
With those wonderful eyes of his he was watching for another grasshopper or for a careless Meadow Mouse.
"The Burgess Bird Book for Children" by Thornton W. Burgess
We found the grasshopper mouse uncommon in Harding County.
"Mammals of Northwestern South Dakota" by Kenneth W. Andersen