— Clay Harper (@ArborwayMatters) April 15, 2015
The pinecone is a symbol of Resist X Reason. We haven't spoken to the folks at Resist X Reason, but from their Instagram account, it seems Jamaica Plain resident Ivan Richiez is one of the people behind it. The South Street man has been a prominent advocate against "stop and frisk" policing, among other issues.
Here's a video Richiez did with the ACLU about his experience being stopped again and again by police in his own community: