I recently took a nighttime excursion to a nearby city with my Eton E5. I was keen to escape my usual static-filled surroundings and collect some mediumwave logs. Mediumwave logging was a success, and I also explored frequencies below 500 kHz. I found four morse code beacons, three of them new loggings for me.
• 335: "CC" (Concord, CA; 36 mi)
• 344: "FCH" (Fresno, CA; 159 mi)
• 374: "LV" (Livermore, CA; 41 mi)
• 404: "MOG" (Montague, CA; 286 mi) (previously logged)
Source for exact frequencies and locations: LW Radio Beacons. That page lists 24 beacons in California, so I have plenty more work to do.