Hey, Not an iterator, but it works.

use strict;
use warnings;

use Scalar::Util qw(reftype);
use Data::Dumper;


my $oWkBook    = {
    students =>[
        {fname=>'joe',lname=>'bloe',age=>'18'},
        {fname=>'jill',lname=>'bill',age=>'16'},
    ],
    teachers => [
        {fname=>'joe',lname=>'sloe',age=>'38'},
        {fname=>'jill',lname=>'sill',age=>'36'},
    ],
    admins  =>[
        {fname=>'koe',lname=>'moe',age=>'58'},
        {fname=>'dill',lname=>'mill',age=>'56'},
    ],
};

print reftype($oWkBook);
my @test = getScalars($oWkBook);
for (@test) {
    $$_ .= "test";
}
my $link = \$oWkBook->{students}->[0]->{fname};
print $link;
$$link .= "test";

print Dumper($oWkBook);
print Dumper(@test);

sub getScalars {
    my $it = shift;
    my $type = reftype($it);
    my @out;
    if (defined $type && $type eq "HASH") {
       for my $key (keys %$it) {
           if (!defined reftype($it->{$key})) {
              push @out, \$it->{$key};
           } else {
              push @out, getScalars($it->{$key});
           }
       }
    } elsif (defined $type &&  $type eq "ARRAY") {
       for  ( @$it ) {
           if (!defined reftype($_)) {
              push @out, \$_;
           } else {
              push @out, getScalars($_);
           }
       }
    } elsif (defined $type &&  $type eq "SCALAR") {
       push @out, $it;
    } else {
       return \$it;
    }
    return @out;
}
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Left some of my fumbling in there, you can feel free to ignore that part. ;)