New York Public Library Digital Gallery
Image above, 1. Smyrna blomfildia, Mexique; 2. Papilio polic; New York Public Library ID: 74797; Creator, Séguy, E. A.
I found this lavishly colored image of butterflies in an ornament and pattern collection in The New York Public Library archives. The library offers a vast online digital gallery with hundreds of thousands of images including, old textile designs, historical maps, vintage posters, rare prints and illustrated books. If you are looking for affordable yet interesting pieces for your walls, good quality matte prints can be ordered -- framed or unframed. Prices start at $30 per print, and available sizes are 8 x 10," 11 x 14," 16 x 20," and 20 x 30."
Taking inspiration from the Steven Gambrel-designed room below, you could search the Library's gallery for obscure botanicals that are unlike any you've seen before and order three large-scale prints.
Photograph above, William Waldron for Elle Decor, March 2005.