I believe (and it wouldn't be the first time I'd be wrong about something) that Mr. Muffin may have 'em all; I'm looking forward to seeing his collection one day.
I too, have a fraction of what Atlas has produced. The Illinois Onion Growers reefer is the one O gauge item at the top of my wish list. The town referenced on the car is where I grew up; I can still remember smelling the onion sets!