Shirt-button

[…] though Mrs. Norris could fidget about the room, and disturb everybody in quest of two needlefuls of thread or a second-hand shirt button, in the midst of her nephew’s account of a shipwreck or an engagement, everybody else was attentive […]

He had frequently restored to me sixpences and shillings carelessly dropped upon the floor, for I am apt to be very reckless in such shirt-button affairs [i.e., involving things of low value].

A couple of his shirtbuttons were missing, the dark hair of his chest protruding through the gap.