If you're looking for a painting to use for your assignment, there are lots of websites with images. Go one step beyond Google; look for a museum site that may be more reliable than a general Google search, or an artist's home page. For example, if you Google "van gogh sunflowers" you can look for a museum site in the results.
If you're looking for music, see if the musician has an official website. The musician doesn't have to be living to have a site. YouTube can also be a great place to find sample music, whether you're looking for Tchaikovsky or Janis Joplin, or someone in between.
Poetry, short stories and books may be available online through Google Books, Project Gutenberg or other websites. Go one step beyond Wikipedia; look for a digitized version of the book. For example, if you are looking at the Wikipedia article on the Book of Kells, there is a link at the bottom of the article that will take you to a digital copy of the entire book at Trinity College.
There are photographs everywhere on the Internet, including shots of architecture that you may want to use for your artifact, from the ruins at Siem Reap, Cambodia to homes designed by Frank Lloyd Wright.
Remember that Google and Wikipedia are great for everyday searches, but now that you're in college it's time to start expanding your horizons.
Do you need background information on the creator of your artifact or the artifact itself?
Consider the following resources and check the Searching Basics guide if you need help using the library databases.
Type a creator's name or the title of an artifact into the search box.
Cadillac Ranch, Amarillo, Texas
Art doesn't have to be in a museum and sometimes many people contribute to the creation of a piece.
What can you find out about Cadillac Ranch in Amarillo, Texas from Wikipedia? Is there anything in the library about Cadillac Ranch?