sequence values question

Hi, how can i know the values generated by a column of type serial?
I mean, i have the following table

productos
(
  id serial,
  desc varchar(50)
)

select * from productos;

+-----+------------+
| id  | desc       |
+-----+------------+
|   1 | ecard1     |
|   2 | ecard2     |
|   3 | ecard3     |
|   4 | ecard4     |
|   5 | ecard5     |
+-----+------------+

I insert a row using a SP, i want to return the id and desc of the new
product in the table.
this is an example of the hypothetical SP

CREATE OR REPLACE FUNCTION insert_row(text) returns text language plpgsql
AS $$
DECLARE
  vdesc alias for $1;
BEGIN
    INSERT INTO productos (desc) VALUES (vdesc);
    RETURN (new id ???) || ',' || vdesc;
END;
$$
LANGUAGE 'plpgsql' VOLATILE;


I know i can get the last value using currval(text), and add 1 to the next
values, is this the only way?, what if i want to insert several products?,
should i  return a record ?
thanks