Got laid off, now management wants their stuff back… Do I have to?

I was laid off a couple of weeks ago and was presented a separation agreement that I ended up not signing. The payout wasnt much, but part of the agreement would have been that I return all office keys and passes and my computer. Since I didn't sign the agreement and take the severance money, do I legally have to return anything to them? Im not doing this out of some vindicativeness, I'm just not doing them any favors ever again.