How to pitch a research idea to a professor as an undergraduate?
A small point about language: in the U.S., in mathematics, it might be more tactful and less presumptious (also) to not ask about "work with me", but "advise me on" [the project you propose]. At least to my perception (=old guy) this leaves many more options for the precise relationship. E.g., experienced people can often and easily give helpful advice without really actively participating. At the same time, depending..., they might find interest in doing so. Or, at the same time, they might see that it's better to let you do it yourself... etc.