There isn't a common landform that starts with the letter "Y". Landform names are often descriptive of their features (mountain, canyon, etc.) and don't usually start with "Y".

However, here are some possibilities:

* Y-shaped valley: This could be a valley that branches out like a "Y".

* Yardang: This is a wind-eroded landform, but it starts with "Y" only in the scientific name, not a common name.

Let me know if you're thinking of something else!