Here are a couple pics from the past - three odd color Rainbos posted by the late Patry Denton back in 2007 and a group of harder-to-find Rainbos posted by the late Guy Gregg in 2004 or so.
Vacor did have some "old fashioned" marbles and I could not find any pictures of the older style from pre-90's but their newer old fashioned style is the basic colors with nothing swirly like Winnie's. Here's a pic of a bag of their new old fashioned style (for info - some might look like WV swirls).
Agree on the Vitro horseshoe style cat's-eyes but a little (lot!) nicer than the ones found in bags like this.
The only contemporary cat's-eye that I recall (I don't collect contemps) is one Ro Purser did back in the 1974-75 time frame - zaboo had posted the picture some years back.
Ro Purser's 1974-75 cat's-eye (in Calif) (Zaboo-10-04).bmp
Great ideas so far. I would include a package or two of marbles - maybe the newer Mega nets so people can see what is currently available to buy for their kids to play with.
When I first saw the picture in small size, I was hoping it was one of the Vitro Blackies in the odd style that we see in packaging but rarely in the wild - but, alas, it does look Akro.