This vary in case to case basis. Here is a sample on Filing a Petition to Remove Conditions on Residence for those who are married to a U.S. citizen and still is married. File this form with in the 90 days before the second anniversary of the date you accorded conditional resident status.
COVER LETTER
I- I-751-Petition to Remove Conditions on Residence
* with a Mailer
*Filing Fee/Biometric Fee Money Order $590
* initial evidence : answer to #9
*Permanent Residence Card (copy of front & back)
II- Evidence of the Relationship
A. Wedding Moments
1. Wedding Cards
2. Wedding Pictures
3. Wedding Invitation
4. Wedding Ceremony
5. Wedding Guestbook
III-Evidence of the Relationship
B. Wedding Certificate
C. 2 General Affidavit of Friends (known you since you became a greencard holder)
D. Joint Bank Accounts
E. Joint 2009 Tax Return
F. Joint Ownership of Home
*certificate of the title of the car
*title and abstract
*owner's policy
*special warranty deed
*commitment for title insurance
G. Health Plan Coverage
H. Welcome Letter from HOA
I. Joint Responsibility for Liabilities
* Mortagage Tax
*HOA Fee
*Maintenance Fee
J. PICTURES