At the very least, you should use this as an opportunity to talk to her about what to do/not do with your stuff.

Maybe tell her that you could have given it away to charity, or to a friend if you didn't want to keep it, or you were going to use it for getting around town.

At the very least, I think she owes you another bike off craigslist, not that she'd do it. It's just completely idiotic and unreasonable for a parent to throw away something without even asking if it was wanted.