Is there a Linq method to add a single item to an IEnumerable?

Question

Basically I am trying to do something like this:

image.Layers

which returns an IEnumerable for all layers except the Parent layer,

Answer 1

You can do something like:

image.Layers.Concat(new[] { image.ParentLayer });

which concats the enum with a single-element array containing the thing you want to add