Yes, that's right, they're polyhedral dice.
They are not, however, ordinary polyhedral dice.
When I started playing D&D in 1976, we needed the appropriate dice. The dice we needed were the five platonic solids. Unfortunately, these were very hard to get hold of; indeed, there was only one company making them in world at that time, Creative Concepts (aka Educational Concepts, because they made the dice for sale to schools) of Palo Alto. I think the dice may have been included in the D&D set we bought, or we might have had to obtain them separately; either way, we clubbed together to get them. Thus, when we left for university 2 years later (is that all? It seemed much longer), we split them up between us. I got two, my brother got two, and my friend Greg got one — the 20-sider, which we deemed the most useful and desirable die in the set. Later, my brother gave me his two, so I wound up with four. I've been looking for one of the 20-siders for years.
These are low-impact dice, and they get rounded corners through lots of use. Also, the numbers come off in sweaty palms, so you have to repaint them every so often. The manufacturers stopped making them years ago, and those people who have their own sets are generally very attached to them, so it's very difficult to track any down. Yet here are five, in their original packing, with the original price sticker on them ($2.00). I'm absolutely thrilled with them!
They're a gift from my friend Frank. Palo Alto is his home town, and when the Creative Concepts offices were being cleared out in 1991 he managed to get hold of a few sets. The above is one of them.
My wife doesn't know what all the fuss is about, but any other D&D player from the early days will know exactly how special they are.
If I could figure out a way to display them without taking them out of the packet, I would.