She's fine. Thank you for your concern. For a few minutes I was afraid I'd have to take her to the vet to get her head out. She was
really stuck, and I was afraid I would cut her on the sharp edges. Fortunately I managed to get it off her head and, aside from being covered with soup, she was no worse for the wear. I did have to wash the soup off around her neck where she couldn't reach it well, though. She didn't like that.
You're right, Janet, I probably should look for a new garbage can. The thing is, cats usually have the sense not to stick their heads in places narrower than their whiskers. This one, though, seems to be lacking in the good sense department.
And yeah, I felt bad for her, but it was also pretty funny.