I don't know how much you know about Russian Folktales and Illustrations but I think among the souvenirs one can bring back from Russia I think there should be also an illustrated book of Russian fairy tales. Russian folktales' books are really fascinating and most of the time their illustrations are astonishing. Even if these books are supposed to be for children their are not easy to read at all.
The most popular stories are the ones collected by Александр Афанасьев (Aleksandr Afanasyev) and the Pushkin's ones. Aleksandr Afanasyev was the first great Russian folklorist and collected several fairy tales until the middle of the 19th century. The collection is called Народные Русские Сказки (Russian Fairy Tales).
These works are full of Russian pagan and christian symbolic meanings and rytuals, and from these stories come out fascinating and frightening figures as Баба-яга (Baba Yaga), Кощей Бессмертный (Koshchey the Deathless), and the Серый волк (grey wolf). Characters and stories are quite brutal and violent in general, and it seems to me they weren't even meant for children; for sure they were not intended as bedtime reading. Many others details of these tales help to create a gloomy atmosphere, starting with the fact that the stories begin with Жили были (Zhili byli), “There once lived” instead of “Once upon a time”, Однажды (Odnazhdy), and at the end not everyone will live happily ever after.
Many Russian writers and artists, like Pushkin, Gogol, Tolstoy, and Dostoevsky were influenced by Russian folklore and fairy tales. In particular, Pushkin was the first Russian author who used folkloric traditions in his own creations. It's believed that he drew inspiration from the tales he heard from one of his mother's serf, Arina Rodionovna. Among Pushkin's most popular fairy tales we remember especially"Сказка о рыбаке и рыбке", (Skazka o rybake i rybke) and "Сказка о золотом петушке", (Skazka o zolotom petushke).
Eventually, not just writers but also artists and composers were influenced by folktales. Vasnetsov, Bilibin, Vrubel, Roerikh, and Kandinsky are some of the most famous. The first two especially, Виктор Васнецов(Viktor Vasnetsov) and Иван Билибин (Ivan Bilibin), created several wonderful illustrations that decorate the best editions of Afanasyev's and Pushkin's folkstories. In addition, Russian folktales' illustrations have a unique, almost exotic, style and are marked by the power of the brushstrokes and use of color.
That's why I think a book of Russian folktales illustrated by amazing artists like Bilibin and Vasnetsov could be a really cool souvenir to bring a part of Russia home with you.