Frost, of course.
e.e. cummings. Whitman. Bukowski. Sandburg. William Blake. Ginsberg. William Carlos Williams. Gary Snyder. Thich Nhat Han. William Butler Yeats.
Oh, and Rumi, for sure.
Here's a great book. In addition to Rumi, a poet named Kabir was a fantastic mystic poet from the same era. Robert Bly translated them into very easy English.
https://www.amazon.com/Kabir-Ecstati.../dp/0807063800