Freddie...
The field in Flushing that you are thinking of is Laguardia Field...the Metropolitan Oval is in Ridgewood, Queens right off of Metropolitan Ave.
There is also Kisena Field on Kisena Blvd, and that is in Queens as well, I think its FLushing.
When I was a kid, my NY Croatia Youth team played on Randalls Island on the field that is at the open end of the Stadium. I remember what a big thing it was when we played inside the stadium. We also played Hajduk Split of Croatia inside Downing Stadium in 1990. My father used to watch the Cosmos play there too.