Since nobody has answered yet, Ill give it a go. This has happened multiple times and will keep happening. After all, this is the land of the free and the home of the armed. Modern examples would include things such as unrecognized separatist militia, or even 'cults' (Waco TX). The rules prevent this type of discussion, so I'll bring this baby back to the first decades of the 20th century. It sounds like your question is asking specifically for examples of defiance and organization against the government, and one of the most successful (still not very successful) of these came from the anarchist/socialist movement that swept america after The Great War. There was a lot of fear towards "Hyphenated Americans" near the end of the war, and this created animosity towards the president and government from immigrants. After the war, the revolution in Russia goes down and Americans realize the working class could be much better off. A few years later, we have the General Strike of Seattle (1919). Meanwhile, the man most often attributed with starting the movement, Luigi Galleani, had been leading a small following to what he thought would be a revolution as early as 1902. This all culminates in April 1919, when a network of Galleanists sent somewhere around 35 booby trapped letters and packages to people perceived as "the bad guys" in typical communist and anarchist literature. This included newsmen, congressmen, and even John D Rockefeller. One of these packages was addressed to a field officer for the Department of Justice Bureau of Investigation (The pre-FBI) who had been investigating the group after an arrest in 1918 for printing propaganda newspapers during wartime. The reason I answer with this story is that they built and sen these bombs while under investigation, and the watchful eye of Uncle Sam. These packages were not small. They each contained a stick of dynamite and a small amount of Sulfuric Acid. Two of these bombs were discovered before they were meant to be detonated. One by the mayor of seatle who oppossed the strike mentioned above, but the package was opened backwards and did not explode. The second was addressed to a Georgian senator who helped pass the Immigration Act of 1918, but was opened by his housekeeper who lost a hand. Quickly, descriptions off these packages were widespread, and a vigilant mailman detected 16 of these packages, and another 15 or so were later found before reaching their targets. Before the government could mount a formidable response and make arrests, the anarchists struck again. On June 2, 1919 they detonated a series of bombs simultaneously across the country, this time addressed to government officials responsible for sedition and deportation laws. The bombs were MUCH bigger. Each package contained 25 lbs of dynamite and these attacks took only the life of a New York cop, and one of the anarchist members in a premature explosion. These packages all came with a pamphlet, which is my favorite part of this tale. The note was titled Plain Words.

The powers that be make no secret of their will to stop, here in America, the world-wide spread of revolution. The powers that be must reckon that they will have to accept the fight they have provoked. A time when the social question's solution can be delayed no longer; class war is on and can not cease but with a complete victory for the International proletariat. The challenge is an old one, oh "democratic" lords of the autocratic republic. We have been dreaming of freedom, we have talked of liberty, we have aspired to a better world, and you jailed us, you clubbed us, you deported us, you murdered us whenever you could. Now that the great war, waged to replenish your purses, and build a pedestal to your saints, is over, nothing better can you do to protect your stolen millions, and your usurped fame, than to direct all the power of the murderous institutions you created for your exclusive defense, against the working multitudes rising to a more human conception of life. The jails, the dungeons you reared to bury all protesting voices, are now replenished with languishing conscientious workers, and never satisfied, you increase their number ever day. It is history of yesterday that your gunmen were shooting and murdering unarmed masses by the wholesale; it has been the history of every day in your regime; and now all prospects are even worse. Do not expect us to sit down and pray and cry. We accept your challenges and mean to stick to our war duties. We know that all you do is for your defense as a class; we know also that the proletariat has the same right to protect itself, since their press has been suffocated, their mouths muzzled; we mean to speak for them the voice of dynamite, through the mouth of guns. Do not say we are acting cowardly because we keep hiding, do not say it is abominable; it is war, class war, and you were the first to wage it under cover of the powerful institutions you call order, in the darkness of your laws, behind the guns of your bone-headed slave. No liberty do you accept but yours; the working people also have a right to freedom, and their rights, our own rights, we have set our minds to protect at any price. We are not many, perhaps more than you dream of, though but are all determined to fight to the last, till a man remains buried in your Bastilles, till a hostage of the working class is left to the tortures of your police system, and will never rest until your fall is complete, and the laboring masses have taken possession of all that rightly belongs to them. There will be bloodshed; we will not dodge; there will have to be murder: we will kill, because it is necessary; there will have to be destruction; we will destroy to rid the world of your tyrannical institutions. We are ready to do anything and everything to suppress the capitalist class; just as you are doing anything and everything to suppress the proletarian revolution. Our mutual position is pretty clear. What has been done by us so far is only a warning that there are friends of popular liberties still living. Only now we are getting into the fight; and you will have a chance to see what liberty-loving people can do. Do not seek to believe that we are the Germans' or the devil's paid agents; you know well we are class-conscious men with strong determination, and no vulgar liability. And never hope that your cops, and your hounds will ever succeed in ridding the country of the anarchistic germ that pulses in our veins. We know how we stand with you and know how to take care of ourselves. Besides, you will never get all of us * * * and we multiply nowadays. Just wait and resign to your fate, since privilege and riches have turned your heads. Long live social revolution! Down with tyranny! THE ANARCHIST FIGHTERS.

Attorney General Mitchell Palmer, a target of the first package bombs, warned congress the anarchists could "on a certain day...rise up and destroy the government at one fell swoop". Enter J. Edgar Hoover (soon to be the head of FBI), who was appointed by Palmer to head a task force to raid and deport potentially dangerous immigrants, leading to a witch hunt known as the Palmer Raids. On November 7th, 1919, (the second anniversary of the Bolshevik revolution) they performed violent raids on members of the Union of Russian Workers in 12 cities. These raids were highly criticized for being far to violent, and Palmer was criticized for reaching at any link to communism or anarchism. These included later raids by Hoover early in 1920, often arresting American Citizens not eligible for deportation along with members of "communist" groups. This led period of time is then known as The Red Scare, and you can research more into the arming of anti-government forces and attempted revolutions during this time period. Again, this is just the best example I could think of.