not really folklore, but a true story about ships in the great lakes bringing trees to port. One of these ships went down and the Cap'tain's wife continued the tradition of bringing trees for over 20 more years. a Song about it has been done by Lee Murdock, whose music has many nautical . http://www.leemurdock.com/

Rouse Simmons (ship):

A schooner built in Milwaukee in 1868. Because it brought Christmas trees from northern Wisconsin to Chicago each Thanksgiving, its captain, Herman Schuenemann, became affectionately known as "Captain Santa," and the Rouse Simmons became popularly known as "The Christmas Tree Ship." Fully loaded and ready to sail, the Rouse Simmons set out in a storm on Nov.23, 1912, and despite the crew's best efforts, sunk off the coast of Two Rivers in Manitowoc County. View more information elsewhere at wisconsinhistory.org.

see also:

http://christmastreeship.homestead.com/

and:

http://www2.jsonline.com/news/state/Wis150/stories/0111sesqui.stm