As is often the case campaigns run out of swag between elections. Members of congress run for office every two years and go through lots of bumper stickers, buttons and campaign literature. In 2014 the campaign of Suzanne Bonamici issued some great 'Another Good Friend of Bonmaici' buttons and matching bumper stickers. They also have t-shirts with the same logo.
They ran out between the 2014 and 2016 campaigns of the buttons and stickers and re-ordered more for this year. It turns out they must not have used the same place to order pins as you can see from the photo below the two union bugs are different.