Deeds, mortgage information, documents showing improvements (like a pool) and where the funds came from. If you have a basis for value, even something like the Appraisal District's valuation, provide that to your attorney.
Titles, mortgages, and the Kelly Blue Book appraisal.
Statements for bank accounts, credit card accounts, retirement accounts, Roths, IRA's, certificates of deposit, etc. Make sure to know the amount of the account on the date of marriage, if possible.
Copies of all policies and who the beneficiaries are.
Statements on mutual funds or stock accounts, documents on any stock options and when those options vest.
If one of you is involved in a business, the Articles of Formation, By-Laws, any partnership agreements, and copies of certificates of stock. The most recent tax statements are helpful as well.
W-2s, tax filings from at least the last three years, K-1's, and 1099's.
Copies of the most recent health insurance information.
Social Security Information
If children are involved, the State of Texas requires the social security information on both parents to set up the initial child support account.
Cell Phone Records
Both parties' cell phone records, which can be used to expose paramours or perhaps otherwise affect litigation.
Any police reports or convictions of either party or significant others.
Property on hand
Records of cash, jewelry, and other valuable assets in the house are commonly requested and if you have a spreadsheet of these, it is helpful.
Evidence of future income (debts outstanding), pictures of the family, videos, diaries, calendars, email correspondence, school work of children, anything related to the children or parties. This is a catch all category which some attorneys request and some do not. Interestingly, attorneys are also starting to request copies of hard drives, so be prepared.