Got to Michaels or Hobby Lobby, they have tons of viney, ferny types of plastic plants. Pet stores such as PetSmart or PetCo have cool things for aquariums that look like huge tree trunks. that's what I used for the following pics;

http://www.joedios.com/dioramas/sho...r&imageuser=216

http://www.joedios.com/dioramas/sho...r&imageuser=216

If you can't afford Michaels or Hobby Lobby, try looking at your local Thrift stores, goodwill, Salvation army and such! They sometimes have tons of crap like that!