My maternal grandmother was Eleanora Römer (Roemer) Scheihing, born in Climbach, Hesse, whose ancestry I have researched back to the 16th century.
Unfortunately there is no such thing as a "Roemer family crest." Roemer, Römer in German, was and is a very common German surname, not associated with any particular village, town, state or region of Germany. Accoring to Hans von Balow in his "Dictionary of German Names":
"Römer (Röhmer) mostly means a pilgrim headed for Rome, also a merchant who travelled to the Romance countries. Pilgrimages to Rome were undertaken as penance for murderous deeds."