The website K5Learning.com offers reading comprehension worksheets for second graders. As of 2015, other sources of worksheets for reading and reading-related skills for second graders include TLSBooks.com and Education.com.
K5Learning.com offers many of their worksheets for free use. They also have additional materials available for purchase. Their free and paid materials cover reading and other subjects, and are available for multiple grades.
TLSBooks.com also offers free worksheets for reading and other language arts. These are available for second grade as well as other grades.
Education.com offers worksheets, printable games and activities for teaching and practicing reading skills. These materials are free.