maybe try the dollar stores, saw some bird nest that were small at the dollar tree last week, you could always cut flowers down,pine cones and moss would look nice if doing a country style, cut a small peice of fake pine for a tree, or use a small branch off of something out doors,you can paint them also
just a few ideas, hopefully someone else will have ideas for you.
Happy Crafting!
oddie

Big Lots had a bunch of inexpensive scrapbooking supplies. I got a mini Kitty there and some cute flowers that were supposed to be hair pins. Scrapping has mini metal things, but often they are pricey at scrapbook stores. Cheap jewelry from tnrift stores is another source. I look for flowers cuz that's what I want right now, but you see trees birds and seashells on pendants and earrings fairly often. I don't know where you are but its too wintery here for yard sales, but if you nave them look at scrapbooking supplies and jewelry there. I got a little glass tree pin at a stained glass store for $1, they had little flowers and flags and some other stuff too.
good luck, and post a pic for us when you are done!
kathy

Google miniatures for scale dollhouses, gardens, railroads etc, there's lots out there!

Thanks everyone.