After years of thinking about it, I finally made a project for observations from home in Washington, DC. For context, the lot (including the house) is under 4000 sq ft (371 sq m). A few observations slightly outside our lot are probably also included. Since all of the observations are obscured to protect the precise location, I'll describe the area as "inner suburban". It's still pretty densely populated, but most residences in the neighborhood have small yards. Many homes share one (or two) walls with their neighbor, but some are stand-alone.

A few stats as of April 10, 2020:
323 wild species
83 cultivated species

I look forward to watching these numbers grow! I have a number of past observations to add, and more garden species to better document over the seasons.