This is the recipe: 1 reflection, 1 LINQ-to-Objects!
someObject.GetType()
.GetProperties(BindingFlags.Instance | BindingFlags.Public)
.ToDictionary(prop => prop.Name, prop => (string)prop.GetValue(someObject, null))
Since I published this answer I’ve checked that many people found it useful. I invite everyone looking for this simple solution to check another Q&A where I generalized it into an extension method: Mapping object to dictionary and vice versa