I have vague memories of seeing a sign on US-101 marking "Rattlesnake Summit", which is indeed a real location. However, more recently I don't see the sign anymore, and I wondered if I was just going crazy.
Turns out I'm not crazy; there used to be a signpost (GSV May 2012 (https://www.google.com/maps/@39.7874445,-123.5443762,3a,75y,200.06h,83.07t/data=!3m9!1e1!3m7!1sbOfaF4QiRtL2pZY422nJIg!2e0!7i13312!8i6656!9m2!1b1!2i29)) but it's gone in the next snapshot (GSV May 2018 (https://www.google.com/maps/@39.787513,-123.5443123,3a,75y,190.55h,85.17t/data=!3m10!1e1!3m8!1spj8Cv8XPwTPNY_uOJIZOuw!2e0!5s20180501T000000!7i13312!8i6656!9m2!1b1!2i29)). In fact, it looks like the wooden post is still there! Just the sign itself is gone.
I always liked seeing the sign, as it is a cool name and it felt like the wilder, more adventurous complement to Ridgewood Summit (https://www.google.com/maps/@39.341991,-123.3156924,3a,75y,326.11h,77.34t/data=!3m6!1e1!3m4!1s9pdfrhZafwHF1dC7HA-Acw!2e0!7i16384!8i8192) farther south. What happened to it?
(https://i.imgur.com/VuEsjYh.png)
Most likely it either got hit by a car or stolen. You might write to Caltrans and ask; it's possible they have no idea it's missing.
Cool, I shot an email to the "District 1" email listed on the Caltrans website, it's in their hands now.