2 Syllables: SU
Arden, ardent, aren, arson, Aryan, Austrian, bargain, Barton, carbon, Carleton, Carlton, Carmen, Carson, Charleston, Charlton, Clarkson, darken, foreign, garden, garland, garment, guardian, harden, Harlem, Hartmann, hearken, jargon, margin, Marian, Markham, Marston, Martin, Martin's, parchment, pardon, parlance, Parsons, Sargent, sergeant, Serjeant, sharpen, Spartan
3 Syllables: USU
4 Syllables: UUSU

Found 49 words across 3 groupings. Skipped 22 excess words of a similar stem.