The currency in Mexico is the Mexican Peso, although the currency sign is the same as the dollar ($).
As at today, the current exchange rate between the Mexican Peso and the United States Dollar is 0.07 pesos to the dollar, therefore a $2 coin would be worth almost 15 US cents.
Sadly in this day and age there's not an awful lot you could buy for 15 cents in the US, or even for MXN $2 in Mexico. A bottle of water will set you back MXN $8, a one way ticket on local public transport, MXN $7, or a pair of Nike's a whopping MXN $1084.
Most places in the US will only change coins of values MXN $10 or higher, so you might have to hold on to your $2 until the next time you're back in Acapulco!