It's legal if one side of the conversation is aware.

Both sides need to be aware. In some instances a verbal mention of a
recording must be announced. In others, an intermittent audible tone or beep
is sufficient to constantly remind both parties that a recording is being
made.

Which of the above is accurate depends on what state you are in.

Incorrect. It's a federal determination (wire tap). Local state regulations
cannot apply here since one party could be in Maine, and the other in
California.

Local state regulations apply unless the parties ARE (not "could be")
in different states. Chances are if Mom is listening on her child
talking to his friends, they (all three) are in the same state.

Who's law would apply ?

In some states, the recording is OK if one of the parties is doing
the recording (and therefore knows about it). In others, it's not.
ALL parties have to know.

I'm not clear on what you are trying to say. It sounds like you state one
thing and then contradict yourself.

Different states have different rules. Some require ONE party to know,
others require that ALL parties know. Read the front section of your
phone book; chances are your state's rules are mentioned there.

But, again, recording/wire-tap laws are determined at the federal level. Any
state laws are superseded by federal law anyway.

This isn't the case if the federal law defers to the state. It's
my understanding that federal law requires that AT LEAST one party
knows about the recording, and that some states have stricter rules.

Just like California has a state law allowing medical pot use. The federal
government doesn't recognize this law and will prosecute anyone using
"medical" pot. It's a hot topic. Federal always has and always will take
precedence over state law.

Only if the laws conflict. For example, the Federal Do Not Call List
didn't abolish all the Do Not Call Lists in states that had them.
A law can explicitly say that the states are free to impose higher
penalties. Federal regulations capping speed limits on highways (for
energy-conservation purposes) don't prevent states from putting
a lower speed limit on a section of highway (for safety, noise,
revenue enhancement, or other reasons).

Gordon L. Burditt