Andy Chase

This is probably well documented if you look in the right place, but having just spent a number of hours puzzling through it on my own (despite) having access to documentation, I think it bears reiteration:

If you use '#value' when declaring a form element, that value is what will be received after submission, even if applied to a textfield that gets changed by the user. (This makes sense when passing a value behind the scenes, as you would do with a '#value' form element)

Use '#default_value' if you want the end-user to be able to modify the value.