To expand on my colleague's answer, your question asks "is it legal for my employer to fire me for discussing my wages with fellow employees?" and, as stated, the answer is "yes."
This is because most states abide by an "employment-at-will" theory, which states that an employer may fire an employee, (and conversely, an employee may quit) for any reason or no reason, including bad or irrational reasons. An employer may NOT terminate an employee for an "illegal" reason, and this generally falls into one of two categories: (1) on the basis of a protected characteristic (because of race, gender, age, disability...) and (2) for reasons against "public policy" (refusing to violate the law, reporting discrimination...).
One other type of "protected activity" includes the exercise of rights under the National Labor Relations Act. This includes "protected concerted activity," generally for the purpose of improving working conditions. However, based on what you've included in your question (simply discussing raises), this wouldn't apply.
Discussing wages is not the type of "protected activity" that triggers an exception to an employment-at-will status. Therefore, unless you have a specific contract stating that you can only be terminated for "just cause," your termination is simply for a bad or irrational reason, but not an illegal reason.
Sorry you've had to go through that, though I'm afraid there's no legal recourse available.
No attorney-client relationship is created, or intended to be created, by this answer. You should contact an attorney licensed to practice law in your State for assistance in analyzing your specific situation.
Maybe not. It is an unfair labor practice if your employer terminated your employment because you were acting with at least one other employee to improve conditions of employment (i.e. wages). If this is the case, you should make a complaint with the National Labor Relations Board http://mynlrb.nlrb.gov/. There is a very short deadline (off hand I think 6 months) to make such a complaint so if interested you should not delay. You may also want to consult with an attorney on this matter.
This does not sounds like something covered under the National Labor Relations Act, but I encourage you to explore that further. If it was a general discussion about wages, there is likely nothing you can do. Florida operates, for the most part, under the at-will doctrine when it comes to employment relationships. This allows for the ending of that relationship by either party for any or no reason as long as it is not an illegal reason, with or without notice. I do encourage you to file for unemployment. While termination may take place for this (silly) reason, you will not be denied your benefits for this reason, most likely. Only reservation is whether you had been previously warned of this or if it was a know violation of the employer's policies.