There are a lot more than those we know the traditions and customs Mapuches. Many have been assimilated or integrated to the western culture and many other unfortunately have gotten lost with the time and discrimination.
The more relevant is Ngüllatün (ngülla: to request, tün: action) whose duration is of three days and it's made once a year. It's the action of which requested to Nguenechén, people's master, God represented in the sun that is dual: man and woman. It's the moment of the contact with God.

What is requested is protection, help and climate's regulation of which the cultivations, animals and their same existence depend. It's also the moment to thank: mapuches takes offerings (best animals) that will be sacrificed and burnt when concluding the meeting.

An indispensable requirement is full moon because is related with fertility. Date and request are decided by lonkos. They also designate to which will be in charge to direct it, lifetime duration charge. 

Another encounter reason of smaller importance that previous one is Ahuiñ. It's the encounter of travelers that go in oneself address. They can be hunters, collectors, etc. They meet to cross for the sorcerers Mojones where the sorcerers pass controllers are. They make a beat to horse around the mojón and rotate in sense of the needles of the clock at the time that they make offerings until the sorcerer is "satisfied." When crossing to the other side of the pass they make the same thing but the turns are in the other sense. The meaning of this action is to erase the infraction of having been in the heights dedicated to the peace and the ice that are the houses of the their ancestors souls. For example in Tromen Pass is a stone of Chilean side and a pine of Argentinean one.
In what concerns to the legends for being the Mapundungun a solely oral language the same ones constituted the history, ownership and Mapuches cosmos vision.

Among them is the story of Trentrén and Caicai. The same one is located in the times where there were alone mapuches in the region. They count that once had appeared a man that had said to be correspondent of Nguenechén and that everything will flood because Caicaifilú would get angry and should go to Trentrén mahuida to survive. But nobody had paid him attention. That year they made the raining rogation going to the lake and hitting the water with pehuenes branches. But it rained so much that never stopped. Then Caicaifilú (mythological that represents the wrong, with snake form. Metaphor related to rivers and streams) got angry and with it line it hit the water so that ascends more and called Pillán (deity that lives in volcanoes) of Mahún (rain). Everything began to be flooded and some that remembered to the correspondent of Nguenechén began to ascend to Trentrén (snake that represents the well and that in the flood saved mapuches). It's said that from that time they were with dark color skin for being near Äntu (sun). Trentrén woke up of so much mess and curved to help to ascend to mapuches. Caicai wanted to take out mapuches of the cave where they were sheltered but Trentrén hit it and threw it to the bottom of the lake, dropped a rock above and died. At once stopped to rain and they made a rogation in gratefulness to Trentrén to have bran them. It's said that the mountain is stopped in four paws and if it rained this way again it would get up again. 

Another legend of animals this time is about the encounter among ngürü (fox) and choique (ostrich). It counts how ngürü was able to win choique trust saying that if it wanted to have some shoes should only bring a leather and would make shoes. Choique like had the paws all hurt of the earth went to look for it. But ngürü tied the shoes so strong that choique could not walk more and finished being devoured.