I submitted my resignation with 30 days notice. My employer said she
would accept, but I could go in 2 weeks and they would not pay the
other 2 weeks.

It appears to me that in not accepting my resignation as presented,
she fired me with 2 weeks notice. Is this an accurate assumption? Can
I be fired because I resigned, or is this "constructive dismissal?"

I agree with your interpretation that you were fired with two weeks
notice.  I can't tell whether you have a case for wrongful
termination.  You may be interested in this discussion:

http://members.cruzio.com/~dkane/Wrongful_Termination.html

What kind of an employment contract do you have?  Does it require 4
weeks notice by either party?  If so, then it would seem that the
employer is obligated to pay you for the 4 weeks, although she may
allow you to terminate your work within that period.  If the contract
did not specify 4 weeks notice  - or you were hired "at will" -  as
the following excerpt from Efn-ga's link states, you can be fired for
"no good reason".  Your giving notice indicates your disinterest in
the job, and often employers prefer not to have someone around is
planning to leave, thus I expect that she would be within her rights
to let you go on two weeks' notice without paying for the additional
two weeks.

"This is because in California (and most if not all other
jurisdictions) employment is presumed to be "at-will."  In other
words, the employer can usually fire the employee at any time for a
good reason, or for no good reason.  They just can't fire the employee
for a bad reason."

Since it seems that you volunteered your resignation without making
claims of harassment or another "bad reason" that would preclude the
employer's firing you, it seems unlikely that "wrongful termination"
applies.

Of course, please note in the disclaimer below that this in neither
legal or professional advice.

Sorry that my comment does not support your wishes.  As you know,
comments are free and are NOT an official answer to a question  - and
can be wrong.
Regards, Myoarin

Thank you for these replies.

>>>Sorry that my comment does not support your wishes.

But it does support my wishes in a way...  since I am now fired I am
eligible for unemployment insurance.

No situations are simple. I gave 4 weeks notice out of a good heart
and willingness to help the company. They actually need me around for
the 4 weeks, and I was happy to help. My employer asked me to go on
contract after my "two weeks" on the job as a salaried employee end,
so I can complete the work, but at much less money, of course. This
seems like exploitation to me, and another good reason to leave this
company, right?

Again, thanks for your views.

Hey, well, that is a new aspect.  Glad it's worked out to your satisfaction.
Myoarin