file manda.htm/php

<form method='post' action='nomepg'>
<input type='text' value='valore1' name='val1'>
<input type='text' value='valore2' name='val2'>
<input type='text' value='valore3' name='val3'>
<input type='submit' value='Invia' name='Submit1'>
</form>

file prendi.php

$val1=$_POST[val1];
$val2=$_POST[val2];
$val3=$_POST[val3];

<input type='text' value='valore1' name='$val1'>
<input type='text' value='valore2' name='$val2'>
<input type='text' value='valore3' name='$val3'>