Does anyone know where these images originated from?

Try tineye.com, but chances are with that design work you aren’t going to get it free, or cheap.

If your website is noncommercial, I don’t think you have anything to worry about at all. For example, zealous holders of copyright, of which Disney is a prime example, don’t have the attorneys or investigators that would be needed to police every use of a Disney icon as someone’s personal avatar, copying their images to Facebook pages, etc. And the truth is – they LOVE that use of their images. That’s free publicity for them.

Where the problem arises is when someone wants to use a Mickey Mouse icon in a commercial way – which hasn’t been approved and licensed by – and the required fee paid to Disney. That is, using their work and property for free to generate your own income.

Now, if you’re making a private website that you expect to exploit for commercial gain at some time, you should be thinking along those lines from the start, as you seem to be. But if it’s never going to be commercial, then you should feel free to grab and use whatever you like. Your only real risk in that sense is being scorned as “derivative”.

Try this.