Are there any examples of assonance in William Wordsworth's poem, "The Daffodils"?
I don't believe so.
Perhaps, you are picking up on the fact that although there is no real assonance, the meter and words of the poem, give a feeling of quiet, swaying, beauty.
Good poets can take us to anther world in our imaginations with out ever having us leave our "couches." Thus, the relatability (is that a word?) of the poem to so many readers over so many years. His experience conjures up visions of our own from the past and helps us add some beauty to this dreary world.