What other beans / veg work in chilli con carne?

[PoesyCherish]

I want to make chilli con carne but fed up of the same old recipe. We typically use brown onions, red kidney beans and chopped tomatoes. As well as changing it up a bit, I'd also like to bulk it out so it goes further and costs less per portion.

What other veg or beans do you put in?

Sliced courgettes, mushrooms, red pepper, puy lentils, carrots, onions, kidney beans in chilli sauce, celery