Or search: crew, gang, knot, tuft, swad, clump, flock, bundle, cluster, tussock, caboodle, pleiades, assemblage, clustering, agglomerate
2 Syllables: SU
cometh, compass, cumbrous, Dundas, dungeons, frontage, functions, fungus, hundreds, hundredth, junctions, London's, lunches, monkish, numbness, oneness, onions, plunges, pumice, pumpkins, punches, punish, someone's, sponges, sumptuous, tonnage, umbrage, unctuous, wondrous, youngest
3 Syllables: USU
assumptions, Columbus, conjunctions, consumptive, encompass, injunctions, presumptions, presumptive, unpunished

Found 39 words across 2 groupings. Skipped 3 excess words of a similar stem.