I sketch in code

<?php
	$target_url = 'http://127.0.0.1/accept.php';
        //This needs to be the full path to the file you want to send.
	$file_name_with_full_path = realpath('./sample.jpeg');
        /* curl will accept an array here too.
         * Many examples I found showed a url-encoded string instead.
         * Take note that the 'key' in the array will be the key that shows up in the
         * $_FILES array of the accept script. and the at sign '@' is required before the
         * file name.
         */
	$post = array('extra_info' => '123456','file_contents'=>'@'.$file_name_with_full_path);
 
        $ch = curl_init();
	curl_setopt($ch, CURLOPT_URL,$target_url);
	curl_setopt($ch, CURLOPT_POST,1);
	curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
	$result=curl_exec ($ch);
	curl_close ($ch);
	echo $result;
?>

<?php
$uploaddir = realpath('./') . '/';
$uploadfile = $uploaddir . basename($_FILES['file_contents']['name']);
echo '<pre>';
	if (move_uploaded_file($_FILES['file_contents']['tmp_name'], $uploadfile)) {
	    echo "File is valid, and was successfully uploaded.\n";
	} else {
	    echo "Possible file upload attack!\n";
	}
	echo 'Here is some more debugging info:';
	print_r($_FILES);
	echo "\n<hr />\n";
	print_r($_POST);
print "</pr" . "e>\n";
?>