It's an adorno, or a decorative piece applied to a larger piece of pottery. Extremely common in Mexico, Central America, South America and the Caribbean, but less common in the US. They are classic souvenirs from a lot of touristy places, but I don't recognize that style. Many of the styles from the big sites in Mexico were almost mass produced in ancient times, and are very easy to identify.
If you find pottery shards in your area, do they look like that? The color and stone temper are unique looking.