I Was Arrested For Failure To Identify. What Is The Lowest I Can Plea Bargain For?

It will depend on the Da, judge, your previous criminal history etc.
You will not get anything approaching a detailed answer here.
Typically on your 1st court appearance, you will have an opportunity to talk to a baby DA, and ask them what they can offer. In my experience a hefty fine and/or some sort of probation (likely unsupervised) will be very likely. It may involve you actually pleading guilty to the original charge or they may substitute a different, lesser charge, (like disorderly conduct etc) which you plead guilty to.
You have to appear in court, regardless of who you plead.
If you plead not guilty and are found guilty expect the maximum sentence allowable.

I do not know why you failed to identify. I think the judge will ask you why unless you just forgot to carry your I.D. Try to plea bargain and get a good lawyer too. People can forget their wallet and ID cards, etc.