How many times congress or the house of representative agreed on something unanimously?

Any bill that becomes law has to pass both the House of Representatives and Senate (referred to collectively as Congress). All bills that become law are available through the Statues at Large.

No list of unanimous roll call votes in the House of Representatives exists to our knowledge. The roll call information for each bill is available in the Congressional Record. The Senate has a comprehensive list of how to access the Congressional Record. You can also use Govtrack, which has roll call vote information from 1998 to present.