The key message in there is "OAuth verification failed", which means that the information sent by BB doesn't exactly match what WeBWorK is expecting.
Did you have this working previously?
The first thing to check is exactly what the message suggests: make sure that the Consumer Secret that you have set in WeBWorK (probably in /opt/webwork/webwork2/conf/authen_LTI.conf) matches what you have entered in WeBWorK, and also that the URL used in BB matches the URL in WeBWorK, which includes checking $server_root_url in /opt/webwork/webwork2/conf/site.conf.
I also discovered that in my case leaving the Consumer Key blank in our LMS (we use D2L) caused problems. As long as it was set to something then it worked.