Parker

Named for William C Parker, a civil engineer, who made a map of the town in February 1862, following the survey of William R. Hutton’s. The survey included the land northwest of the creek and the streets nearby. 

What's interesting to me is that I have been to the San Luis Obispo City Public Works department, and the historical society, and neither have a copy of the maps done by Hutton nor Parker?

Here is the 1860 federal census record that lists William as being 27 years old and is from Ireland. Can't find any information about where he went after this.

And here's an article that describes some of the land transfer issues that happened between the Mexican Government and the new residents who patented land claims for the same property.