Why does Eddie say that he doesn't like daffodils? What do these flowers mean to both Eddie and the young narrator of "The Day They Burned the Books"? How do they both feel about the English—and why?

When Eddie says that he doesn't like daffodils it is, implicitly, because they are a symbol of England. What Eddie doesn't like is England. The daffodils have no inherent qualities or characteristics that Eddie dislikes. He simply dislikes them because they are a symbol of the England which his father is always saying is better than the West Indies, where they live now.
Eddie and his friend, the narrator, also dislike daffodils because they always have to read English poems in their school (presumably a school for English expatriates) which are "in praise of daffodils." The allusion here might be to the poetry of Wordsworth, an English poet who liked to write about daffodils. Also, the narrator dislikes the English children he meets, describing them as haughty and condescending. The English children call the local children "horrid colonial(s)."
In short then Eddie and the narrator dislike the English because they are haughty and rude, and also because the English expatriates don't seem to embrace the culture of their new home in the West Indies.