The text of reports can be found in a number of resources including those recommended and listed below. Reports are also sometimes found on committee web sites and also are contained within Compiled Legislative Histories.
Westlaw provides the following:
Legislative History - United States Code All congressional committee reports, 1990 -
Also selected reports, 1948 -1989
Lexis provides the following:
Committee Reports 1989- (In the main search box, type "committee reports" Select Committee Reports from the sources listed in the drop down menu)
USCCAN (U.S. Code Congressional and Administrative News All congressional committee reports, 1990 - Also, selected reports, 1948 -1989 Main Collection KF48 .W45
ProQuest Congressional provides:
House and Senate Reports 1817 -
Go to Advanced Search, select House and Senate Reports 1817 - Present. Recommended: When searching, use the "All fields including full text" option, from the pull down search menu.
HeinOnline provides:
Reports included in the U.S.Federal Legislative History Library.
Congress.gov provides:
Text of Committee Reports, 1995-