Argentina Or Peru?

Very strange coin.

Your coin closely matches the specifications of a modern US cent, so I will assume that this is made out of zinc or a similar lightweight, cheap alloy.

Although your coin appears to be old (using many design features typical of a 19th century Latin American coin), the denomination tells us that it's modern. The Peso was as introduced by Spain was a silver coin on which the US dollar was based. 20 pesos would have been a denomination issued in gold until the world began to abandon the gold standard in the 1950s/60s. Since then, inflation rates have been all over the place, ranging wildly between countries.

Since your coin is at most 50 years old and has neither date nor country of origin, the most likely explanation is that you have a trade token. There isn't a whole lot to go on, but your coin probably dates to the 70s or 80s when many countries in South America were experiencing runaway inflation and rapid money devaluation.

Actually, severe inflation did occur in 19th-century Latin America, this being the reason we see the little nickel 1 & 2 pesos "p/m" (for Papel Moneda, paper money) coins of Colombia circa 1900, which are otherwise identical with the regular 1 & 2 centavos.

That said, the style of the wreath side looks 20th century. I'd say Argentine — Peru never used the peso as a denomination.