Hello!  Thanks for your questions.  I am originally from Pennsylvania, too, and that’s where I learned many of the plants I can identify as well.  I suggest picking up a field guide for plants in your area, such as the Peterson Field Guide to Medicinal Plants and Herbs: Of Eastern and Central North America.  I’m sure you can find even more specific guides for plants in Florida, as well.  Also check out Botany in a Day by Thomas J. Elpel.  You could go on a little nature hike using the guides as help to get acquainted with the new plant allies in your area! 

As far as depression goes, St. John’s Wort is the clear winner in my opinion.  Passionflower, oatstraw, and lemon balm are also very effective - I’ve written about all of these herbs on my blog, so check past posts if you’d like to learn more!  These herbs work best over a longer period time, so don’t expect immediate results; the SJW should not be taken with any other anti-depressants.  I will also mention that these herbs are best suited for only mild cases of depression.  If you’re going through a very major depression, you absolutely need to see a professional doctor!  I understand not wanting to take pharmaceuticals, but talk to a therapist at the very least.  (This is coming from a place of deep concern, because I’ve totally been there before.)