These journals are scholarly, peer-reviewed research, just like journals in the LCC databases. The difference is that open access articles are paid for by the government, foundations, or advertisers, so they're freely available to readers.
Google Scholar can help you find resources for academic research papers. Keep in mind that Google Scholar misses a lot of material that's only available by subscription. If you're asked to to pay for access to articles, look up the title of the journal where the article was published in the LCC Library Catalog to see if you have access to it for free.
If you have trouble accessing an article, ask a librarian to help!