Road sign posts

I occasionally come across road signs (speed limit, no parking, etc) that have been hit or otherwise damaged and are laying in the woods or along the road in a heap.
What is the scrapper etiquette on scrapping either the galvanized poles or the aluminum signs themselves?

Those signs still belong to the county, I wouldn't touch them. Unless you had a receipt of purchase you could be in some trouble if the scrap yard decides to call the police. A lot of counties will auction those signs off or scrap the stuff themselves.

I would contact the city or county road/highway maintenance dept and ask.

I usually dont take speed limit and other official signs but I will take the private ones if they are in the right of way, just seperate the two pieces and then drop em in the iron bin.