I think you are referring to what is called Crop Circles, which are geometric formations made by flattening part of the crop (i.e. stepping on it using a piece of board). Many people believe that these formation are made by UFOs.
Here is some information about the Salt Lake City Crop Circles:
Additionally, the following website explains in more detail the general phenomenon and history of Crop Circles::
Hope this helps.
Hello JuneBug and thank you for accepting the answer.
If you think there is no resemblance between them and the crop formations shown in the web pages, then I think the Salt Lake City Chamber of Commerce or the city offices would be the right place to ask.
What you can do though is try to find them yourself using the free GoogleEarth satellite imaging program, or by simply using the Google Maps website, and zoom in on them. Not only will you be able to see real photo images of then from the sky, you will also be able to get their exact locations (coordinates). Here is an example of what you will be able to see with these wonderful tools:
If you need assistance in finding, downloading or using these tools please let me know.