It looks like a passionflower, like P lutea.

That is Wild Cucumber (Marah macrocarpus), a native plant to Southern California. If the area is not getting any irrigation other than rain, it will die back by summer.

If it is growing in a spot where you don’t want it, remove it. If it adds to the appearance of the border, then leave it.

If you want to remove it, please note that Marah species grow from tubers and it will pop back up next rainy season. The tubers can be huge and digging them out can be tough. This is why one of their common names is "Manroot" as the "root" can be the size of a grown man.

Whoa! OK, I will treat it as a neutral party that comes to visit once a year. Don't want to dig out a man sized root! Also, it covers the jade that I'm not particularly enamored of, so... let it be.

Thanks so much to you all as always!

I've got some more mystery plants coming down the pike...