Favorite way to create trees for site plans in photoshop

Hi all,

  Just doing some experimenting with Photoshop and site plans and was wondering if anyone had any examples of techniques to add vegetation, sites where you can get different trees and plants. etc for use in site plans.  So far I have been using the landscape architecture brush set that has a number of different tree symbols, but am looking for something a little different.  I’ll post some pictures when I get a chance.

Thanks for any input.

Jon