Hi Matt! It's great that you're working on a senior paper about the poetry works of W.B. Yeats. Evaluating your thesis statement, it seems like there are a couple of areas that could use some improvement.
Firstly, the statement that Yeats, like most Modernist poets, has changed poetry by using his own techniques and styles may be quite general. To make your thesis stronger, consider specifying the particular techniques and styles used by Yeats which make his poetry stand out.
Secondly, stating that his poems are considered "one of the best" might be difficult to prove definitively. Instead, you could focus on the unique qualities of Yeats' poetry and how it contributed to the Modernist movement.
A revised thesis could be something like: "W.B. Yeats' innovative use of symbolism, mythology, and lyrical language in his poetry contributed to the transformative nature of the Modernist movement, setting his works apart from his contemporaries."
To support this thesis, you can compare Yeats' poetry to that of other Modernist poets such as Dylan Thomas and Seamus Heaney. By analyzing the themes, techniques, and stylistic choices employed by these poets, you can highlight the distinctive qualities of Yeats' work.
In terms of finding related poems by other poets, reading their works would indeed be helpful. Take note of the themes, tones, and literary devices they employ and compare them to Yeats' poetry. This will enable you to make a strong case for the uniqueness and significance of Yeats' contributions to the Modernist movement.
Good luck with your paper, and if you have any further questions or need additional assistance, feel free to ask.