Welcome to the forum!
These are from your Picasa web albums. I loathe gallery since it syncs these albums even if you uncheck it in your settings - accounts & sync.
I also hate how Gallery cannot fully render 12MP files (when you zoom in they get pixelated way too soon) and that you cannot sort folders/albums by oldest first.
I switched to the QuickPic app. Much better, no picasa integration, pick your media folders and better rendering.