What can I do with Pork Butt Trimmings?
What can you do with pork fat?

Cook the bits over med-low heat to render out the fat. You can strain the rendered fat and use it as lard- make biscuits or pastry. Or you can get crafty and make soap or candles- but these are not within the scope of this site.

I had some Kazakhi friends in Russia who made a dish called "Плов" (Plov).
http://www.say7.info/cook/recipe/118-Plov.html
They would render pork fat this way and continue until the fatty bits were well fried. They would then scoop out the fried bits (and eat them) then fry onion and then carrot in the fat. Add some pork and fry until browned. Then add rice and water and a head of garlic on top, cover until the rice is done. Delicious.