In the novel Of Mice and Men by John Steinbeck, the author gives us many lovely descriptions - of whispering grasses, lapping lakes, silence, wilderness and even the ranch. He chooses to begin with a landscape background as he wants to set the scene not only for the Great Depression rural theme but also for the background to the relationship of George and Lennie. The quiet lonely spot gives the author the opportunity to show the reader the friendship by itslef, without any group dynamics going on to cloud the waters. In the small events we can see clearly the responses between the two friends. The bushes, lake and wide open space peppered by all the towns they will need to run to or hide in help us to see Lennie's motivations and George's challenges.
Steinbeck wrote the novella Of Mice and Men as part novella and part stage play. As you know, stage plays begin with a description of a setting/scene as part of the stage directions. There are four major settings: the river, bunkhouse, the stable buck's, and the barn.
The men enter and exit as if on a stage. In Chapter 1, the sandy bank of the Salinas River is described and then:
"They had walked in single file down the path, and even in the open one had stayed behind the other."
In fact, there is a stage play of the novella directed by Sam Harris. There are three acts:
Act I: scene i: by the Salinas River
scene ii: the bunkhouse
Act II: scene i: by the Salinas River
scene ii: Crooks' room
Act III: scene i: the barn
scene ii: the Salinas River
The stage directions read:
"Two figures are seen entering, L. or R., it makes no difference, in single file, with GEORGE, the short man, coming ahead of LENNIE."
In my opinion, Steinbeck begins with a description of the setting as sort of a way of putting the first "bookend" on the story. By this I mean that he's doing it for stylistic purposes because he is going to end the book (the other bookend) the same way.
At the beginning of the last chapter of the book, Lennie comes back to this same place. Only this time he is coming (though he doesn't know it) to die. So it sort of makes stylistic sense to begin and end the book with the same setting.
You could also say that he begins with a description because he wants to point out how peaceful and serene it is. This place is somewhat of a haven compared to the outside world that the two are soon going to have to enter.