It has tiny teeth along the leaf margins, so it's likely a Sempervivum or Jovibarba. It could also be a young Aeonium of some sort. I hope that narrows the field of possibilities.

Brad- The three varieties you mentioned grow quite a bit larger than my plant although the Jovibara sometimes referred to as "rollers" has me wondering.

Some history- This plant started as a cutting from a Gentleman's personal collection. He brought it over as a cutting himself from a remote village in Mexico over 40 years ago. He has a large collection of these that he's been propagating for years. According to him (Mr Roger Martin,) it is a slow grower and only a handful of people in California have this plant. Those that do have it all originate from him.

I asked him what it was but, he didn't know the name of it.

Mr. Martin's Jovibarba? the Jolly Roger?

Just being silly. I hope there is a botanical classification for it, but it could be new to science. I have a small cactus, Geohintonia mexicana, which was only discovered in 1992, and required its own new monospecific (isn't that a great word?) genus.

None of the possible plant types I mentioned are native to Mexico, or even the New World.

Not a Jovibarba I think. I would search in the direction of Graptoveria / Sediveria / Graptosedum. Somrting like that.

Harry

Brad- I like the Jolly Roger name..I'm sure Mr. Martin would also, lol

Harry- I don't think they had those x crosses back then, especially growing in the wild. Keep in mind it does not grow any larger than what I have in the picture. I suspect it may be a type of sedum/stonecrop.