It depends on what you really consider to be 'true communism'. Countries like China and Cuba are moderately successful countries which run under what they call communist governments. That being said, both countries have many features that are fairly un-communist like. Other countries run under Socialist governments which isn't true communism but is similar in a lot of principles.
No one has every really figured out how to make the economy run in a 'true communist' state. You have major issues of a centralized government controlling means of production to amply support the demand in the country. It is amazingly difficult to estimate demand of a product beforehand and centralization is also not great at addressing changing market conditions. This is a really short explanation of a much bigger issue of an 'ideal communist' economy and it really is a lot more complex as to why no one has really figured out how to make it work yet. This is why most countries that implemented a communist government quickly adopt at least parts of a free market economy, which is un-communist by nature (you can actually make an argument that it is not but traditional communists disagree with the premise of a free market as it basically has inequality built in it to some degree).
I don't think the responses here really demonstrate an understanding of what Communism is. In a Communist society, there is no state, no class, and no money. We colloquially refer to the Soviet Union or China under Mao as "Communist" because they were ruled by Communist parties. However, "Socialist" would be a more accurate descriptor. Marxist-Leninist states attempt to form a Communist society through Socialism. No state has ever successfully made the transition. I (as well as many others) would argue that this transition is impossible.
Many people, including myself, would look at Makhnovia as an example of a Communist society. It was an anarcho-Communist society largely based on the principles of Peter Kropotkin and was born out of the Russian civil war and Ukrainian war of Independence. In brief, the Makhnovists (the anarchist equivalent of the Bolsheviks) initially fought alongside Lenin in driving out the Whites from Ukraine. Once this had been achieved, the Makhnovists effictively [banned central authority, they threw open the prisons, blew up police stations, wasted the bosses and returned power directly to the workers] (https://libcom.org/history/1917-1921-the-ukrainian-makhnovist-movement). A system of libertarian free trade amongst villages and cities was also implemented. It's estimated that about 7 million people lived in what is called "The Free Territories" This contrasted greatly with the repressive policies and nationalisation of industry which occurred once the Bolsheviks gained power.
As such, the libertarianism of the Makhnovists was frowned upon by Lenin and Trotsky. They viewed the Makhnovists as rivals, if not counter-revolutionary. The Bolsheviks concocted a story in which Makhnovist soldiers allegedly raided supply trains headed for the Soviet state. The Bolsheviks invaded Makhnovia under the pretext they were protecting Soviet interests. In reality, they were attempting to spread Soviet influence into an area that was anti-authoritarian. A war broke out between the former allies. The downfall of the Makhnovia was when Trotsky let in known he was willing for peace talks with the Makhnovist leaders. The Makhnovist leaders, believing this to be true, went to this meeting where they were met with firing squads.
Makhnovia had a tragically short life. It existed between 1918 to 1921 until it was absorbed into the Soviet Union. If you're interested, you can read about it [here] (https://libcom.org/history/history-makhnovist-movement-1918-1921-peter-arshinov). Peter Arshinov's book is considered to be the most comprehensive study of Makhnovia.
this question may be worth x-posting to /r/AskSocialScience or /r/AskAnthropology
Would the Paris Commune be considered a good answer?