"Aunt Jennifer's Tigers" is a poem about Aunt Jennifer and the tiger-ific tapestry that she creates. The poem's central question is: what's Aunt J's relationship with the tigers? Do they represent her? Or the life she wished to lead? Or everything she can't have in life?
The title gives us a little clue as to how we should answer this question. In the title, the tigers belong to Aunt Jennifer. With that little apostrophe in her title, Rich designates the tigers as Aunt J's property. This fact gets all the more interesting when we read later in the poem that Aunt J's wedding ring is described as "Uncle's wedding band."
"Uncle" may possess Aunt Jennifer's wedding ring and, it's suggested, Aunt J's life, but the tigers are 100% the property of Aunt J. They may not be real tigers, but they're powerful nonetheless. What's more, ol' Uncle can't come near them. Aunt Jennifer's tigers have a life all of their own outside Uncle's patriarchal authority. (And that's grrrrrrrr-eat! Sorry, we couldn't resist.)