Ahhhh,... Blaine you beat me to it!
Be very careful with used components that you have no idea about the history behind them. I too sometimes search for the left behind discarded brass however keep them separate from your own and when you get them home clean and inspect each one for any signs of stress. I will go over every piece that I bring home and mike each carefully after cleaning and visually inspecting.
That brass you find could be someone else's discarded for a reason.
(3-5 loading using hot loads, stretched out or cracked rounds, etc.)
Check the primers also for any abnormal pressure signs. If I find any bad brass I make sure that I pinch the mouth openings closed with pliers so no one else might try to reload them.