Nubbin

Noun

 * 1) A stub, especially a stub of undeveloped corn or fruit or nipple.
 * 2)  A small protuberance, bud, bump, knob, or the like.
 * As an avid button collector, I have had to develop an efficient way of removing the nubbin of thread from the button hole.

Thesaurus
bantam, banty, bilge, blain, bleb, blister, blob, boss, bow, bubble, bulb, bulge, bulla, bump, bunch, burden, burl, button, cahot, chine, chit, clump, condyle, convex, core, crux, diminutive, dowel, ear, featherweight, fingerling, flange, flap, gall, gist, gnarl, handle, hill, hump, hunch, jog, joggle, kernel, knob, knot, knur, knurl, lightweight, lip, loop, lump, matter, meat, mini, minikin, minnow, minny, mole, mountain, mouse, nevus, nub, nubble, papilloma, peewee, peg, pony, rib, ridge, ring, runt, shoulder, shrimp, slip, small fry, snip, snippet, spine, stud, style, tab, tit, tubercle, tubercule, upshot, verruca, vesicle, wale, wart, welt, wisp