Am i eligible to collect PTO after ive already quit?

I worked at a restaurant in massachusetts for almost a year. I got a new job within my study's industry and put in 3 weeks notice. I worked my last 3 weeks and asked if my saved PTO could be put into my last check. Can they withhold it and not give me my PTO? Or should i have used it up before my 3 weeks notice was up? Am i entitled to my saved PTO after i already quit? Thanks