What is the collective noun for a collection of poems by one author?

There isn't one single, universally accepted collective noun for a collection of poems by one author. However, here are some commonly used terms:

Formal:

* Volume

* Anthology

* Collection

* Work

Informal:

* Book

* Verse

* Song (This is sometimes used for a lyrical collection)

You can also use descriptive terms like:

* A Cycle of Poems

* A Suite of Poems

* A Garland of Poems

Ultimately, the best choice will depend on the specific context and the tone you want to convey.