Since I expect Peter to be sharing this room with a sibling of unknown gender in about two years, I went with a neutral barn theme. (The wallpaper is gingham, though it's probably too small to see in the pictures.) Nevertheless, this has turned out quite masculine. Painting the furniture white would probably help, but I can't bring myself to do it. The bed and chair were made by his great-great-great-great grandfather, the tin front to the pie safe was hammered out by his great-grandmother, and the dresser was made by his grandfather.
I wish I could show you the dresser, but next to it hang Peter's real name, and I'm a freak about internet privacy. Above the dresser is a mirror made from an antique horse harness, passed down from his grandmother's barn. Most of our knick-knacks, in fact, come from Mimi's barn. She'll be retiring it when the last of her horses die, and her eagerness to clear things out has timed well with our room decorating!
So even if it's more masculine than planned, the sentiment of this room is high, and I don't think I'll be changing it any time soon: