Will putting a few nails in a poplar tree when it's still.

It seems to me that that should happen. The colorations in the wood are just minerals. That being said, if you put a nail in the tree, you should have iron oxide spread through the wood, producing the streaks of color. If you end up doing this though, you should mark the nails to make sure you don’t hit them while milling the wood.

-- Ethan, https://instagram.com/ethan_woodworker/

An old guy that used to have a sawmill would/or wouldnt saw a log by checking for color streaks from nails or wire in the bottom of the log. If he could see color, he would cut chunks from the bottom til no more stain showed. (obviously a metal detector would have saved him a lot of time, he didnt use one) So anyway, yea I think it would work but I dont know how long it would take, a year or 20 years?

This is an interesting idea although, as benny says, the results would not be harvested for many years. I wonder about putting the nails into the roots where the minerals may be drawn up the trunk with other nutrients.

It works, but they need to be in there roughly 20-30 years. :-)

-- Nature created it, I just assemble it.