That button only appears on the Navigation Toolbar if the menu bar is hidden and you have the orange Firefox menu button and if the Bookmarks Toolbar is hidden as well.

Thanks, but that didn't work for me. I unchecked both the menu and bookmarks tool bar. I got the orange Firefox menu button, but still no bookmark button next to the home page button.

Did you drag the bookmarks menu button with the drop marker on a toolbar?

Firefox 4 has two bookmark buttons with a star in the Customize window.
One star button has a drop marker that open a Bookmark menu.
The other star button without the drop marker opens the bookmarks in the sidebar.

Drag the bookmarks menu button with the drop marker on a toolbar.

Thanks, it worked. I now have the button, but there is not enough room for it to be next to the home button in the navigation bar.. It sets under it in the bookmarks bar. It is also smaller and has sharper corners. The other bookmark (side bar) button is closer to the image in size Neither buttons match the ones in the navigation bar. Not what the intro to FF4 showed, but that is OK.

You get the Bookmarks Menu button on the Bookmarks Toolbar if that toolbar is visible. I usually place that button on the left hand side of the tab bar and hide the Bookmarks Toolbar.