Once the Baal Shem Tov was traveling during the winter in Russia with one of his close disciples, Rabbi Moshe Shoham. As the country roads in Russia were usually covered with snow during the winter, they were traveling in a sleigh.

It became the 15th of Shevat, and they realized that they had no fruit with which to celebrate the holiday. So the Baal Shem Tov told his wagon driver, Alexei, to drive the sleigh off the main road and into the fields.
...not only was it not cold there, but the climate was tropical!
They went for a short distance and came upon a field that not only was not snow-covered, but had in it an orchard of oranges. Moreover, not only was it not cold there, but the climate was tropical!

They immediately went over, picked some of the oranges, and joyfully made the blessings, including the shehecheyanu blessing for enjoying a fruit for the first time in a year, to celebrate the holiday.

Rabbi Moshe Shoham also took a few oranges back to the sleigh, to have for later. All this time, he did not even wonder how it was possible for an orange orchard, which requires a tropical climate, to appear suddenly in the Russian countryside in the middle of winter. In fact, oranges do not grow in Russia at any time of the year! But being that he was often in the company of the Baal Shem Tov, he was so used to seeing wonders that this miraculous event did not even cause him to marvel.

As they started to walk back to where Alexei was waiting with the sleigh, Rabbi Moshe regretted that he had not taken several more oranges.

They got onto the sleigh and started back to the main road. When they reached the main road, the Baal Shem Tov announced that he wanted to rest briefly before continuing the journey.
...when he reached it, there was no orchard!
Rabbi Moshe immediately decided to take the opportunity to return to the orchard. He followed the path of the sleigh tracks to the field, but when he reached it, there was no orchard!

And when he returned to the sleigh, the few oranges he had picked and put in the sleigh had also disappeared. When he asked the Baal Shem Tov about this, the Baal Shem Tov told him, "When I felt unhappy about having no fruit and not being able to celebrate Tu BeShvat, I brought — by mystical means — an orchard from the Land of Israel here. But since the whole point was to perform a mitzvah, not for personal benefit, the orchard and the few fruit you had taken disappeared afterward."

[Reprinted with permission from the rendition posted by Tzvi Meir Cohn on his website, baalshemtov.com.]

Biographical note:
Rabbi Yisrael ben Eliezer (18 Elul 1698-6 Sivan 1760), the Baal Shem Tov ["master of the good Name"], a unique and seminal figure in Jewish history, revealed the Chassidic movement and his own identity as an exceptionally holy person, on his 36th birthday, 18 Elul 1734. He wrote no books, although many claim to contain his teachings. One available in English is the excellent annotated translation of Tzava'at Harivash, published by Kehos.