http://docs.moodle.org/dev/Navigation_API tells me I can add (append) an item to the navbar (breadcrumbs). Can I prepend an item (to come before the first one)?
General developer forum
At present there is no means to prepend an item to the navbar.
This is the first enquiry I've seen about prepending to the navbar however it seems like an obvious feature so I've created a tracker issue MDL-41081 to see it implemented.
I've also created a quick patch as it really is an easy addition to navigation code.
If it gets integrated it will only be integrated for the next major release 2.6.
Why do you want to pre-pend to the navbar? It starts with Home. What could be more logical than that.
Surely you are not planning to pre-pend a different thing on different Moodle pages?
If you want to prepend a fixed link on all pages, e.g. University Home Page, then you can easily do that in your theme.