Oprah Winfrey has given generously over the course of her television career, but during this week's taping for the final two episodes of "The Oprah Winfrey Show," she was on the receiving end of a long line gifts and sentimental accolades. 

The 57-year-old will end her syndicated national talk show with episodes on May 23 and May 24 after 25 years on the air. More than 20,000 screaming (and crying) fans, joined by a long list of celebrities, crammed into Chicago United Center to honor Winfrey during the four-hour event. There were songs, reunions — and one very large green pledge, courtesy of "ABC World News" anchor Diane Sawyer. 

When Sawyer came on stage, a huge tree of lights sprouted in the middle of the arena, according to USA Today. “That is ‘The Oprah Winfrey Show,’ ” Sawyer said. “I want you to know, in honor of your 25 seasons, in front of those 25 new libraries, there will be a giant tree — an oak tree, an Oprah tree, standing and inviting children to bring their books and hopes and fears and know that you are there to embrace them.”

Those libraries Sawyer mentioned were another surprise gift, the work of musician John Legend and Target. In honor of the talk show host's well-known interest in books and reading, 25 libraries will be built or rebuilt and stocked with books courtesy of Target. It’s not clear if the trees to be planted in front of the libraries will be of the full-sized variety (read: transplanted) or saplings. Sawyer did, however, add this awesome detail:

“Not just 25 trees! We are going to plant across this country, 25,000 oak trees for Oprah.”

Why oaks? Well, it turns out that the oak is Oprah's favorite type of tree. In fact, if the world were to end tomorrow (coincidentally, it might), that's where she says she'd watch it all go down. "I have a lovely home in California," she said in a previous interview. "I love sitting under the oak trees. So that's what I would do."

Catch part one of Oprah's farewell special on Monday, May 23 at 4 p.m. EST. 

Also on MNN: Oprah's staff goes vegan for a week

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Oprah receives 25,000 oak trees
Tables are turned on the famously generous talk show host, who is honored with gifts during the taping of her farewell special.