Is it possible to buy an allodial title to real estate, in the USA?

No.

It’s not possible to purchase an allodial title, but it is possible to dissolve all contracts that bind you to paying taxes and obtain a “fee simple absolute” title, which means that those who possess the land are subject to the laws of the county/state/nation but not the the property tax obligation of the municipality/county/state.

Hmmm.

I don't know

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Does allodial title exist in the United States? 

No, in the U.S. the land is subject to eminent domain by federal state and local governments. It is also subject to the imposition of taxes by state and/or local governments. As a result, there is no land under true allodial title.

You bury your house underground and relabel it as farmland.thus you can at minumum,screw them out of every dollar possible.

You can't buy one but if you can prove all the land transfer lineage from when the US first owned or settled the land over all the future decades of all the owners then you can avoid land taxes.

It's very hard to prove it and they all have to be proven documents.

YES A very well kept misunderstood open secret that is very tight lipped. Nobody wants to spill the beans so to speak. The American Bar Association and its members will not aid you if they can help it in pursuance to this topic in the republic of Minnesota.

Minnesota constitution states:

Article I Sec. 15. Lands allodial; void agricultural leases.

All lands within the state are allodial and feudal tenures of every description with all their incidents are prohibited. Leases and grants of agricultural lands for a longer period than 21 years reserving rent or service of any kind shall be void.

Lawyers will gaslight you this is arcane language and is of no consequence but there it is in black and white for all the uneducated in law to understand. Feudal tenures is reference to English common law and magna carta. Some argue the zip code and use of the united postal service invalidates allodial title, well, that is a federal issue as states are sovereign agents.