Well I did send some paystubs as proof when I filled up my applications... Sound people are saying that we shouldn't had sent it but I found this article in USCIS page and if says that paystubs are definitely proof.
I personally think that either way they're not dumb and they know that we all work illegally so i'm not gonna worry because i'm not the only one that worked illegally in this country snd plus I know god is with me.
Here's what the article says:
Proof of identity
Passport or national identity document from your country of origin
Birth certificate with photo identification
School or military ID with photo
Any U.S. government immigration or other document bearing your name and photo
Proof you came to U.S. before your 16th birthday
Passport with admission stamp
Form I-94/I-95/I-94W
School records from the U.S. schools you have attended
Any Immigration and Naturalization Service or DHS document stating your date of entry (Form I-862, Notice to Appear)
Travel records
Hospital or medical records
Proof of immigration status
Form I-94/I-95/I-94W with authorized stay expiration date
Final order of exclusion, deportation, or removal issued as of June 15, 2012
A charging document placing you into removal proceedings
Proof of Presence in U.S. on June 15, 2012
Rent receipts or utility bills
Employment records (pay stubs, W-2 Forms, etc.)
School records (letters, report cards, etc.)
Military records (Form DD-214 or NGB Form 22)
Official records from a religious entity confirming participation in a religious ceremony
Copies of money order receipts for money sent in or out of the country
Passport entries
Birth certificates of children born in the U.S.
Dated bank transactions
Social Security card
Automobile license receipts or registration
Deeds, mortgages, rental agreement contracts
Tax receipts, insurance policies
Proof you continuously resided in U.S. since June 15, 2007
Proof of your student status at the time of requesting consideration of deferred action for childhood arrivals
School records (transcripts, report cards, etc.) from the school that you are currently attending in the United States showing the name(s) of the school(s) and periods of school attendance and the current educational or grade level
U.S. high school diploma or certificate of completion
U.S. GED certificate
Proof you are an honorably discharged veteran of the U.S. Armed Forces or the U.S. Coast Guard
Form DD-214, Certificate of Release or Discharge from Active Duty
NGB Form 22, National Guard Report of Separation and Record of Service
Military personnel records
Military health records