THe ones that are pulled you can json request: https://tiles.services.mozilla.com/v2/links/fetch/%LOCALE%

%LOCALE% example: "en-US"

However currently these are not saved, but the active about:config entry was browser.newtabpage.pinned I believe.[Noah]

The directory tiles that Firefox shows on the about:newtab page are saved in the directoryLinks.json file in the parent location of the disk cache. See the about:cache page for the location of the disk cache and go one level up.

See also:

• https://support.mozilla.org/kb/thumbnails-on-new-tab-page-are-missing

You can change the order of the boxes on the about:newtab page and drag an item to a different tile to pin it to that position or you can remove a website by clicking the close X to block that URL. You can drag a bookmark or history item and drop them in a tile on the about:newtab page to pin them and have your own favorites sites showing.

See this article about the New Tab page (about:newtab):

• https://support.mozilla.org/kb/new-tab-page-show-hide-and-customize-top-sites