We found this great picture of a Princess Peach Cosplayer on DeviantART. Since Princess Peach's last name is Toadstool, it would only make sense that she would have a mushroom tattoo on the palm of her hand, right?
Here's an interesting fact: Peach wasn't always known as Peach, at least not in North America. She was always known as Peach in Japan, but in North America she was known as Princess Toadstool from her introduction in Super Mario Bros. all the way up until Super Mario 64, when she signs the letter to Mario as Princess Toadstool (Peach). Since then, she's become more known for her Peach name than her Toadstool name.
Princess Peach :: Inked by vera-baby on deviantART