You may consider documents as
Must (Copy and paste from From I-765 instruction page 6)
1- application with the filing fee
2- copy of Form I-94 Departure Record (front and back), if available. If you are filing an I-765 under the (c) (9) category, an I-94 record need not submitted
3. A copy of your last EAD (front and back). If no prior EAD has been issued, you must submit a copy of a Federal Government issued identity document, such as a passport showing your picture, name, and date of birth; a birth certificate with photo ID; a visa issued by a foreign consulate; or a national ID document with photo and/or fingerprint. The identity document photocopy must clearly show the facial features of the applicant and the biographical information.
4. You must submit two identical color photographs of yourself taken within 30 days of the filing of this application. The photos must have a white to off-white background, be printed on thin paper with a glossy finish, and be unmounted and unretouched
Other document may be needed and sometimes may trigger RFE; copies from:
1- DL
2- Copy of I-485
3- Previous visa
Documents not required but if you include it will not hurt except for paying more mailing fees:
Cover letter
I-140
Birth certificate
Work appointment
Pay stub
Bank statement
Lease agreement or mortgage certificate
Recommendation letters
SS card
AP
Marriage certificate
Securing your appplication with document will not protect you from RFE to some extent. Just send the required documents and wait.