In both poems, the speaker is walking in nature when he is stopped by a beautiful scene. In "Daffodils," also called "I Wandered Lonely as a Cloud," he is stunned by the beauty of the sudden sight of thousands upon thousands of daffodils in bloom. They are in front of a lake and swaying in the breeze as if they are dancing. The narrator feels joy as he watches them.
In "The Solitary Reaper," it is sound rather than sight that stops the narrator. He is in the Scottish Highlands and sees a young woman reaping in the fields. The sound of her song fills the air. The notes are more beautiful than the song of the nightingale, and though the narrator can't make out the words, he is transported by the tune's melancholy, plaintive melody.
At the end of both poems, the narrator experiences joy as he later remembers the experience he has had.