Currently we are shipping giant sequoia (sequoiadendron giganteum) and sugar pine (pinus lambertiana) seeds. However, the seeds on offer may change without warning.
With my luck a giant sequoia would most certainly take root. I love trees but I have plenty of them in the front and the back yards. A sugar pine might be nice, though. We don't have many pines in this part of Texas but heading east of Dallas one drives into the east Texas Piney Woods. It's beautiful country.
You can order seeds every two weeks and the seed types change. So, if you want tree seeds then check out the link GloryB gave. A minimum of 10 seeds will be sent with each order. Cool.