Formal:
* A cycle of poems: This is often used for a collection of poems that are linked thematically or chronologically.
* A volume of poetry: This is a more general term for a collection of poems, often published as a book.
Informal:
* A garland of poems: This evokes the image of a collection of poems strung together like a garland of flowers.
* A bouquet of poems: This is similar to the previous example, but with the image of a bouquet of flowers.
* A tapestry of poems: This suggests a collection of poems that are woven together to create a larger whole.
* A constellation of poems: This compares a collection of poems to a group of stars in the night sky.
Other options:
* A sheaf of poems: This is a more traditional and straightforward term for a collection of poems.
* A gathering of poems: This is a neutral term that works well for a collection of poems on any topic.
Ultimately, the best collective noun to use will depend on the specific collection of poems you're referring to and the tone you want to convey.