I just met this Pacific Gopher Snake Pituophis catenifer catenifer in my basement (top two photos) I can’t imagine it being a nice place for a snake to hang out because its chilly down there, but we’ve found mice there in the past, so maybe it was on the hunt. (They eat small mammals (pocket gophers, mice, voles), birds & bird eggs and lizards & insects when young or in need.)
When I picked it up for relocation purposes, it puffed up its body, flattened its head and shook it’s tail (mimicking a rattlesnake), which turns out to be the standard defense reaction for a gopher snake. They can be anywhere from 2.5-7 ft (76-213 cm) long (my basement friend was roughly 3.5 ft) and can live up to 15 years in the wild.
The Pacific gopher snakes are found in the coastal areas throughout western North America. The bottom photo was on my front steps in August 2014 (within 20 ft of the basement), that snake was about a quarter of the size of today’s snake. I couldn’t find any reference to young changing color, so I am going to guess that these are not the same snake given the color differences.