There are several variations of tessellating tree patterns.
Point to base
http://www.connecttheblocks.com/shop...u-12010053.htm
Base to base
http://www.simplyordered.com/quiltedproducts.htm
Paper pieced
http://www.quiltdesignnw.com/Q134-Fo...lt-pattern.htm
and many others in these styles. The one posted bt GailB is from Quilters Trading Post.
None of them are free that I am aware of.