Near the tree is a sign that explains more about the project:
I think it's awesome that a relatively small number of knitters and crocheters produced that many pairs of mittens - almost 400! What a wonderful thing to do for needy families, and from viewing the mitten collection in person, I can vouch for how well-crafted they are! They will undoubtedly be the nicest mittens a person of any income level could own.
Although crafters could use their own yarn, First Reformed did supply yarn for people to use as well, as seen in the above sign's photos. And I'm told that the church already has a fresh supply of yarn - so that a new project can begin in 2014. What a nice thing to do, and I felt this church's efforts deserved a post.
Full disclosure: I am not a member of this church, nor did I craft any of the mittens - I don't know how to knit, and I can barely crochet. But I am friends with an extremely talented knitter who's on staff at First Reformed; she was one of the people who got the (yarn) ball rolling on the Mitten Tree. She had kept me informed of this project throughout the year, so of course I had to see the tree in person.