There are 1 book by Harry R. O'Brien on BookOrb. A strong starting point is The diary of a plain dirt gardener (1933). The bibliography below is in publication order, with series grouped in reading order.
Standalone books
Frequently asked questions
How many books has Harry R. O'Brien written?
BookOrb lists 1 book by Harry R. O'Brien.
Where should I start with Harry R. O'Brien?
A good starting point is The diary of a plain dirt gardener (1933).
What is the Harry R. O'Brien books in order list?
In publication order: 1. The diary of a plain dirt gardener (1933).