While dropping leaves off at the township when I was in college, I spotted a big bin of beat up road signs. I asked the worker there what they were and he said they were old signs that they were scrapping. So I asked if I could have one and he told me that nobody would notice of one disappeared when he turned the other way
Even though I got it innocently, apparently it's still illegal. Surprisingly, the only issue I ever had was my college giving me a hard time about it being in our dorm room.
@Black Box may remember.