We first tried carving a scrap of lumber I found in my garage - very bad idea. Next we tried basswood, which was excellent to carve but squished easily making it hard to keep thin lines and we weren't sure how well it would hold up to repeat printings. In the end we used some "white wood" planks from Dick Blick that were sold for woodblock printing. Not the greatest, but they did the job.

Lady Wurm used cheap cutting boards that she picked up from Walmart :)