W. Phillpotts Williams has several books of foxhunting poems, including Plain Poems, Poems in Red, and Poems in Pink.
The Book of Hunting Songs and Sports is a foxhunting anthology primarily, and includes poems.
Songs of Horses, Saddle and Song, and In the Saddle although general horse-related poetry anthologies, include foxhunting selections.
R. E. Egerton Warburton I believe may have some books of foxhunting poems – or at least selections of poems in his book(s). Ditto G. J. Whyte. Possibly Arthur Conan Doyle, IIRC (I know it was someone that kind of surprised me as it wasn’t what I expected given their primary genre).
All these are public domain – try Google Books or Internet Archive for copies.