The imbedded penny by the pool that Hemingway's second wife, Pauline, had built over his outdoor boxing ring while Ernest was away in Europe covering the Spanish Civil War,
writing, and spending "special" time with Martha Gelhorn, who would eventually become his third wife.
When he returned from his travels and saw the very expensive swimming pool (the first in-ground pool in Key West), Hemingway shocked at the cost of the pool stated,
“Pauline, you’ve spent all but my last penny, so you might as well have that!” and flipped the penny on the ground.
Pauline took the penny and imbedded it in the concrete.