What is the wealth that the sight brings to the speaker in "I Wandered Lonely as a Cloud"?

This line from "I Wandered Lonely as a Cloud" is found in this stanza:

The waves beside them danced; but they
Out-did the sparkling waves in glee:
A poet could not but be gay,
In such a jocund company:
I gazed—and gazed—but little thought
What wealth the show to me had brought:

The speaker is describing a simple scene in nature. While on a walk, he discovers a "host" of daffodils growing alongside a lake and blowing in the breeze. He pauses life for a moment and soaks up the beautiful glory of the scene: the way the daffodils seem to "dance" in the breeze, the way they "[toss] their heads" during their dance, and the way they stretch out in a stunning line that accentuates the border along the water.
The natural beauty of this scene provides the speaker with immense wealth—but not in a material sense. He later finds that, when he is in a foul mood, he can bring to mind this image of the dancing daffodils bordering the lake on a gorgeous day, and the memory fills his heart with pleasure. The wealth the daffodils bring to the speaker is the power to overcome negative thinking by recalling simple, powerful beauty.