...on a '67 327 Camaro. I had developed what I thought was a mis-fire, but after replacing all the plugs, wires and distributor cap, it was still with me. More diagnosis pointed to a valve problem. When I removed the right side valve cover, I had the exact same problem as your pictures.
I consulted with an auto parts counter guy and he basically said the same things...place a really stong magnet on the bottom of the
oil pan, replace the push rod and rocker arm, change the
oil and filter and start it up. Engine lasted another 35K before I traded it! Apparently, the piece of metal that broke off the rocker arm just fell down the return
oil gallery into the oil pan and was never made it back to the oil pump. I suspected lifter problems, and everything else. Most probably it was just a weak spot in the rocker arm. Never again had another problem with the engine.
But...I'd still remove the pan, determine what's in it that shouldn't be, change the oil and filter, and replace the damaged parts.
Good luck...let us know what turns up!