Having her applied under the 3 year rule, she took her foreign passport(the one she used to enter the US), IRS transcripts for the last 5 years, mortgage statement and deed, our kids' birth certificates, marriage certificate, my naturalization certificate, 3 bank statements, our DLs, our health insurance cards for the past 5 years, letters from our 401ks showing we are beneficiaries from each other.
A lot of it was unnecessary but I like to err on side of caution so basically she took every document that shows both our names or that show the same address.
Good luck on your journey