Actually, Traci, It  lei , no  s .  There is no letter  s  in the Hawaiian alphabet.  I m no student of the language, but I do know it is one lei, two lei, three lei, etc.  I wouldn t call them necklaces, either.  Lei are garlands of flowers and/or greenery either strung on a string and tied together and worn around the neck or tied down on a flat band and worn around the head. (Haku Lei)
The word is Lei.  The Hawaiian alphabet is limited and S is not one of them.  They do use it now but not before.  It is a garland of flowers, some are tied and others are not.  There is various flowers used.
First off its LEIS. A Hawaiian lei is a necklace made of flowers, like you see hula girls wearing!