Here is what I had send :-
1.$120 processing Fees Write A# in memo line of the check
2.Two (2) photographs. Write A# at the back
3.INS Form I-765
4.Mailer from previous EAD Card
5.Copies of the following supporting documents:
a.Passport pages
b.Copy of I-94 card (front and back)
c.Copy of I-485 application receipt
d.Copy of Current EAD (front and back)
6. A Cover letter to INS explaing why I need renewal.
I guess cover letter is optional, its upto u if u wanna send it.
Put all these documents in envelope. Put $ 120 Check at the top . Use paper clips and rubber band to hold documents together, Do NOT use stapler. (read INS website for details if needed).