I need visa to travel to Mexico?

I was born in Argentina but I'm an American Resident...I'm living in the USA exactly New York City. This Summer I'm Planning to go to Mexico City with my mother .She is from Portugal and she is an American Resident too. My question is Does we need a travel visa. We are going to stay in Mexico just 15 days.
Thanks!!!
Yes, we are Legal residents of the United States...
Thank you so much Charlie!

If you and your mother are legal permanent residents of the U.S., with green cards, you do NOT need visas to go to Mexico. If you FLY to Mexico, you will need passports from your HOME countries. Sometime later than next summer, passports will be needed for LAND travel to Mexico also. You may see the website below and read the 2nd paragraph under the list of countries to see that permanent residents of the U.S. do not need visas to visit Mexico. You will get a tourist card on the plane or at the border , good for up to 180 days. It costs about $22.00 USD.

No, only the U.S. does that.

No, you don't, your passport will be enough !!!