I have a few fixes for this plugin

[johnmain]

Database creation. There isn't a migration for this plugin so the table doesn't get added.

Here is the script to create the table in SQLite.

CREATE TABLE background_image_backgroundimage ( id INTEGER PRIMARY KEY AUTOINCREMENT, img TEXT );

MySQL
CREATE TABLE background_image_backgroundimage ( id int NOT NULL AUTO_INCREMENT, img varchar(255), PRIMARY KEY (ID) );

Also when there is no image in the Database you get an error on the home page.

Here is a fix for the templatetags/background_image_tags.py file

from django import template
from background_image.models import BackgroundImage

register = template.Library()

def background_image_url():
    """ """
    try:
        return BackgroundImage.objects.get().img.url
    except: 
        return ''

register.simple_tag(background_image_url)