The snake, caught in the beak of an eagle, perched on a cactus, growing on a stone, sitting in a lake, is the national symbol of Mexico. It's an homage to the description that the god Huitzilopochtli according to legend gave a group of natives of the perfect place to found their new capital. The story goes that they wandered for hundreds of years before founding what is now known as Mexico City.
Timmy, these nice, large coins are not made from silver, but from cupro-nickel; an alloy of copper and nickel that might walk like silver and quack like silver, but it's not a du-... err, silver.
This is what the catalogs say about approximate values for these coins:
worn: worth face value in Mexico
average circulated: $1 US Dollar approximate catalog value
well preserved: $2
fully uncirculated: $5
A keen collector might pick up a beautiful mint-state specimen for up to $10 US Dollars if it is a particularly appealing coin.
The coin shown in our picture has no wear and is thus fully uncirculated. However, it has picked up a very unfortunate heavy 'bag mark' (a contact mark from another coin during the production) at four o' clock on the rim of the reverse side. As always, each coin stands on its own merits, and I would personally skip this coin and try to find a better one - after all, they made fifty million of these! A coin like in the picture might bring in $2 to $3 from the right buyer.
The values cited on this page are only approximate catalog values, and only apply to problem-free coins that do not have scratches, stains, spots or the like. Be sure to read the 'Important Terminology' page in the menu on the top left to interpret these catalog values.