O. Henry 
The Gift of the Magi 

The story tells of a young husband and wife and how they deal with the challenge of buying secret Christmas gifts for each other with very little money. As a sentimental story with a moral lesson about gift-giving, it has been popular for adaptation, especially for presentation at Christmas time. The plot and its twist ending are well known; the ending is generally considered an example of comic irony.
O. Henry's short stories are well known for their wit, wordplay, warm characterization and clever twist endings. 

About the author

William Sydney Porter (September 11, 1862 – June 5, 1910), better known by his pen name O. Henry, was an American writer known primarily for his short stories, though he also wrote poetry and non-fiction.