How awful OP. You poor thing. That's so bloody mean.
I've left more than one job where I was overlooked for leaving cards and gifts, despite akways contributing to others leaving/birthday collections. I was the nice but quiet one that never got into an in-crowd or work clique.
But then I got a job in another office for another firm. I was only there 6 months (had to leave to have a baby, discovered my unplanned pregnancy 3 wks into my new job!) and I was so moved, but so embarrassed at the same time, when they organised a surprise tea party for me and absolutely showered both me AND the bump with cards, gifts, flowers and balloons.
Nobody had ever treated me like that before. Obviously I'm aware of how lucky I was and burst into tears in the car when they helped me load all my hundreds of gifts in. I really didn't feel like I deserved it. I kept thinking "why the f*ck have they done all this for me?!" it makes no sense.
They even sent more cards, flowers and balloons when the baby was born, even though they knew I wasn't returning.
I hope your new job OP brings you some amazing new colleagues like my last work place.