Dear Bonnie,
 
Cottolene is indeed a shortening product popular around the turn of the
century.  I recovered a similar lid from a ca. 1910 site in Corvallis Or, a
site I analyzed form my M.A. thesis,  and had trouble identifying it myself.
 Unfortunately, I'm in transit to a new job in Minneapolis, and my thesis is
in storage in Des Moines.  If I remember right, I found the reference to
Cottolene while thumbing through Harper's Bazaar issues from around the
turn-of the-century for another project.  The adds for the product are quite
prolific in that periodical from ca. 1900-1910, as I remember right.  If you
need definite confirmation on this, let me know, and I should be able to
track it down within a week or so, if not, I recommend finding some Harper's
to leaf through. Best of luck.
--------------------------------------------------
Bob Cromwell
Historic Archaeologist
IMAC
Minneapolis, MN
e-mail: [log in to unmask]