what are examples of spanish stem changing verbs
Any verb ending in -ABir where B is one or more consonants and A is an o or an e that is not part of a diphthong.
There are some lists here:
I entered "Spanish stem changing verbs" in Google and got some good results. Here is a link to a page that gives a list of verbs.
A couple of examples would be "mostrar" and "encontrar".