They all do it. When children come in to my sewing room, they all manage to find a way to push the pins in at least one pincushion all the way down. If they are really focused and diligent, they can manage to do it on all the pincushions in sight (I have many) and true adepts will find a pincushion with pins that have colored heads and create a pattern while pushing the pins all the way down.
Here you see the pincushion on the left rectified and ready for work; the pins are now all quickly and easily grasped for use, but when I came in to sew this morning every single one was flush against the surface of that cushion. The pincushion on the right has had the “kid-in-the-sewing-room” treatment left in place. No, the hammer is not there to threaten little pin-pushing fingers, but to hammer thick and bulky seams for easier sewing, a very good trick. Alas, I know of no trick to stop kids from pushing pins as far as they will go into a pincushion. I just take a little time to re-stage the pins, make sure no needles disappeared inside the cushion and then go back to sewing. It’s a small price to pay for having such engaging company while I’m sewing, although I think the culprit this time either snuck in on his own or was visiting with my cousin while she was here sewing and I was otherwise occupied.

