In Wikipedia, review "Social Class in Ancient Rome" or "Agriculture in Ancient Rome" since information non-specific topics such as "wealthy landowners" can be harder to find. Look in the footnotes and references for authoritative, academically-oriented sources. Remember that some sources will be available in full text only through the UO Libraries as they are not "free web" sources. Some books at the UO Libraries may only be available in print.
You can get your print books in 3 easy ways - https://library.uoregon.edu/pickup-delivery-remote-teaching