Ostergren rhymes with:
westergren, westergren, cedergren, lagergren, sodergren, westergren, ahlgren, almgren, berggren, bergren, blomgren, cedergren, edgren, elvgren, forsgren, halgren, hallgren, helgren, holmgren, hultgren, lagergren, landgren, liljegren, lindgren, lofgren, lovgren, lundgren, lungren, malmgren, mellgren, nordgren, nygren, ogren, palmgren, rosengren, sandgren, seagren, shogren, sodergren, stromgren, westergren, youngren