What is one piece of evidence that mrs. hubbard gave poriot

One piece of evidence that Mrs. hubbard gave Poriot is a a Wagon Lit uniform button she found on the floor of her room

Explanation:

The Murder at the Orient Express is a crime thriller and mystery novel written by Agatha Christie and is one of her most famous works.

It follow Poriot, a recurring detective in her novels who solves crimes. Poriot unlike his more characteristically charming counterparts in Sherlock Holmes and others often relies on his wit as a war hardened veteran and an old man to solve the crimes that he encounters around him.

In the story, Mrs Hubbard is reluctant to give him any evidence, for the lack of her association with the crime but does end up giving him the Wagon lit uniform button she finds on the floor of her room.