They come in all shapes and sizes. The Bonsai Nut seedling thread.

[RJG2]

Found 8 of these guys growing under my lilacs this spring. Maybe I'll make a forest some day.

I think they are Korean mountain ash (Sorbus alnifolia) from my neighbor's tree about 70 feet away.

 

[casun]

Future JBP exposed root. I have five of them in the works.