Beware cheap straight pins
I had a strange experience this afternoon. I had put a straight pin on a block just to mark the top, and apparently, I accidently ironed over the pin as I was pressing my seams. Later, when I went to remove the pin, it wouldn't budge! The pin has a ball top, and it evidently was painted, not solid plastic throughout. The paint must have melted and stuck to the fabric. I got it off w/o much of a mark, but all those pins went into my "dead needle" jar for disposal. In the picture below, you can see the little bit of paint on the shaft, which is a telltale sign. I have no idea where or when I got these pins, unfortunately.