The Smithsonian's Archives of American Gardens is seeking a
Wikipedian who'd like to lead the creation of an article about them.
This article can be as complex as you desire (please not just a
stub! LOL). Please ping me off list if you'd like to take the lead
on this and I'll put you in touch with them. (And no, you don't have
to be a horticulturalist to do the job!)