The pretty good independent publisher Sarabande Books has an open submission period for writers without agents this month. Check out their list before submitting; they do literary fiction, essays, and poetry.
The one downside is the submission fee of fifteen dollars, but in the literary world that is a very low fee for real* book publication.
Try it, and maybe you’ll have a book!
*Real book publication means that one can walk into a well-stocked Barnes & Noble or thoughtful independent bookstore and find at least two or three copies of books by the publisher there—even if not every book by the publisher is in stock.