Or search: cowman, cowherd, puncher, cattleman
1 Syllable: S
bowel, dour, flour, hour, Howell, our, scour, sour, towel, vowel
2 Syllables: SU
Bauer, bower, countered, coward, Cowper, flower, Fowler, Gower, hour's, housework, Howard, Howard's, louder, outburst, outer, outskirts, outward, powder, power, prouder, scoured, shower, soured, stouter, tower, trousers, voucher
2 Syllables: US
avowal
3 Syllables: USU
devour, empower, encounter
4 Syllables: UUSU
overpower

Found 42 words across 5 groupings. Skipped 26 excess words of a similar stem.