The book is about a family living on a ranch/farm in the American West, sometime between 1970 and 2000. I remember three key details about the book: 

A. The families father was killed by a bull during a rodeo. He was gored to death.

B. At one point in the book, a member of the family is in the hospital with a boy who lost his leg to a lawnmower accident. His siblings visit in the hospital and say they are not allowed anywhere near the lawnmower. The boy is in the hospital to get a larger prosthetic leg attached. 

C. The children live on a ranch/farm and often play in a pasture near the house. They go there to hide at one point, but I do not remember why.