push @rows, @fields;

##</code><code>##

push @rows, [ @fields ];

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dumper;

my @fields = qw/ fred one two three /;
my @out;
push @out,  [ @fields ] for ( 1..3 );
print Dumper \@out;

##</code><code>##

$VAR1 = [
          [
            'fred',
            'one',
            'two',
            'three'
          ],
          [
            'fred',
            'one',
            'two',
            'three'
          ],
          [
            'fred',
            'one',
            'two',
            'three'
          ]
        ];