Answer: I found a website authored by the University of Berkeley which gives the history of their 1920's garden and then provides a plant list (over 2000 plants!). Here's the web address: http://www-laep.ced.berkeley.edu/laep/blakegarden/history.ht...
Be sure to click on all the links on the page. You can print off the plant list and choose your favorites. If this doesn't give you enough background and ideas, you might try a web search (I use Google) using the term "1920's garden design".
Best wishes with your new landscape!
Q&A Library Searching Tips