The following websites can help you find newspapers of the time period in the United States:
Here are a couple of magazines that were popular during the early part of the 20th century:
The Doane Library has several journal article indexes for the time period, but the following is the only one that indexes popular magazines from that time:
Doane Library Catalog - Remember to search people and organizations as both author and subject. Searching by author will retrieve additional primary source material; searching by subject will retrieve both secondary literature and possibly additional primary sources.
You also may find primary resources by using words like "diary" or "memoir" in your search.