This is the symbol left in the crib after the Lindbergh baby was famously taken away.  "There has been no genuinely convincing analytic work done on [this symbol] with respect to the Lindberg story" (Jerry Kroth, The Lindbergh Kidnapping, 2011).  [Note that the three black rectangles are actually holes that were punched in the paper and are not technically part of the design.]  The shaded object in the center is, of course, the "black egg" of alchemy, symbolizing the nigredo (a stage of putrefaction; the final step toward the "philosopher's stone" of enlightenment) and expressing "the precarious balance of the hermaphrodite, exalted by a [threatened] equilibrium" (Johannes Fabricius, Alchemy: The Medieval Alchemists and Their Royal Art, 1994).