Or search: tough, rutty, robust, rutted, sturdy, unsmooth, toughened, corrugated
2 Syllables: SU
buckets, buttocks, buttoned, couplets, Drummond, flooded, hubbub, hunted, puppet, roughened, rusted, Rutland, summoned, upland
2 Syllables: US
beloved
3 Syllables: USU
accustomed, conducted, constructed, disgusted, distrusted, encouraged, instructed, Republic
4 Syllables: UUSU
unaccustomed

Found 24 words across 4 groupings. Skipped 2 excess words of a similar stem.