Foreach value from POST from form

First, please do not use extract(), it can be a security problem because it is easy to manipulate POST parameters

In addition, you don’t have to use variable variable names (that sounds odd), instead:

foreach($_POST as $key => $value) {
  echo "POST parameter '$key' has '$value'";
}

To ensure that you have only parameters beginning with ‘item_name’ you can check it like so:

$param_name="item_name";
if(substr($key, 0, strlen($param_name)) == $param_name) {
  // do something
}