You are the Captain. The flight attendant comes up front during boarding, hands you a good size pair of scissors and explains that a pax gave them to her. The pax said that the TSA missed them (shocking, I know) and she (the pax) was just trying to do the right thing by giving them to a crew member. Other pax noticed the handoff so returning them discretely is not an option. The FA is not comfortable carrying them around for the rest of the day. Calling a TSA rep could cause the airport to be cleared out and everybody to be re-screened, which won't help you get home anytime soon. Just throwing them awaystill leaves a potential weapon inside of security. You are not "legally" allowed to posess them while inside of security and the TSA just loves to do random searches at the doors near you crew lounge.