The Texas grid (ERCOT, specifically) is almost completely isolated, in order to avoid certain Federal level regulations. There's no real way for California or any other state to sell power into Texas or buy power from Texas.

Part of what happened with California is that Enron would schedule to deliver a bunch of power over transmission lines that were not rated to handle the power. When it came time to deliver the power, this forced a transmission constraint that in turn forced CAISO (CA grid operator) to buy power on the spot market (expensive) to cover the shortfall. Enron then had generation they could sell at a premium. I remember hearing stories of the ISO seeing the trade go in, recognize what was happening, and not have any legal recourse within the market's legal design.