I wandered lonely as a cloud
That floats on high o'er vales and hills,
When all at once I saw a crowd,
A host, of golden daffodils;
Beside the lake, beneath the trees,
Fluttering and dancing in the breeze.

There were so many daffodils that it looked like a crowd of people at a party.

Wordsworth felt as lonely as a cloud does when it floats and has no direction.

Wordsworth was lonely and on a walk when he came across a field of daffodils.

The daffodils were next to a lake and underneath a tree, blowing in the breeze.