Another of Debussy's Symbolist works is his suite Cinq Poemes de Baudelaire, which sets to music five poems from Les Fleurs du Mal, none of which we read. I am not a fan of this suite; I don't think it even sounds like Debussy, but here is a recording of the first piece, Le Balcon. There is a link to some translations in the description:
However, neither of these pieces actually contains any sort of symbols. The closest thing in music to a symbol is a motif, which can simultaneously represent a figure in a programmatic work or opera (like Berlioz's Idée Fixe in the Symphonie Fantastique) and an abstract idea--in the aforementioned work, the motif represents love. This extension, though, opens up works from Beethoven to Shostakovich to the "Symbolist" label. A piece that not only contains such a symbolic motif but also contains the Symbolist characteristic of capturing an abstract idea, thought, or feeling is Gustav Mahler's Second Symphony "Resurrection". Here is a recording:
This long and very complex piece contains innumerable potentially symbolic motifs. The most well-known and symbolic is the rising and falling syncopated (here, I mean alternating long and short notes) scales, which are almost always present either in some form or another, starting at 2:08 in the woodwinds. The most notable and famous of these figures is the eponymous "Resurrection" theme, beginning suddenly at 1:03:24 and first recited in 1:03:41. The Resurrection theme is one of the most famous symphonic melodies ever; it is triumphant and march-like, but contains echoes of the Dies Irae and repeatedly starts to modulate into a minor key. Like Symbolist works, it represents a concrete image--resurrection--in an abstract, non-programmatic setting, and tries to evoke a sensation rather than strictly an image.