The below are the documents submitted by the President to Congress and which Congress spends the next several months legislating over. DREF is the Doe Reference Collection on the second floor of Doe Library.
Budget of the United States Government
The President's budget proposal based on estimates from the previous year's budget and requests from agencies, issued on the first Monday of February.
Budget of the United States Goverment, Appendix
Includes much more detail than the Budget of the United States Government, including funding for each agency and office within the agency.
Budget of the United States Government, Analytical Perspectives
Provides analyses on specified subject areas or provides other significant presentations of budget data that place the budget in perspective.
Budget of the United States Government, Historical Tables
Provides historical information on various appropriations and expenditures with some tables going back to the 1920's.
Economic Report of the President
Reports federal budget receipts, outlays, surpluses and deficits. Some tables go back to 1929.
The following links will help you track current budget bills (aka appropriations) through Congress.
Current Status of Appropriations Bills
From the Library of Congress, shows the current status as the appropriations bill(s) moves through Congress, from 2011-present. Older bills (1998-present) can be found here.
Maintained by the Senate Library, legislative histories of Approprations Bills, from 1986-present. Older legislative histories of appropriations bills, including their hearings, reports and debates, can be searched in the database Proquest Legislative Insight (UCB Only).
An Analysis of the President's Budgetary Proposals for Fiscal Year
From the Congressional Budget Office, evaluates the economic assumptions and budget estimates and presents possible alternative estimates.