Here is the list Christophe Deslandes suggested. It's way much competitive with the 3 Sylvan Library having a heavy interaction with the 9 Dredge cards.

// Lands
11 Forest
10 Swamp

// Creatures
4 Sakura-Tribe Elder
4 Krosan Tusker
4 Stinkweed Imp
4 Golgari Brownscale
4 Crypt Rats
4 Spore Frog
1 Battlefield Scrounger
1 Eternal Witness
1 Shambling Shell
4 Tortured Existence
3 Sylvan Library
1 Demonic Tutor
4 Moment's Peace

//Sideboard:
3 Dark Heart of the Wood
1 Nourish
3 Rofellos's Gift
4 Crumble
4 Naturalize

As you can see, the deck is nice, but quite slow.

First modification, I'd change the Shambling shell for the brand new Uktabi Drake. It's a wonderful turn 1 drop, a graveyard auto-filler and it can be recast for only 2 mana (one for the Tortured Existence activation, one for hard casting), against 4 mana for Shambling Shell. Of course, you loose one dredge card, but this one wasn't the most used.

Second change : Mana acceleration. One of the best mana acceleration is Dark ritual, but it's not so synergic with the deck. So what about Songs of the Damned. As you've got a lot of creatures, some of them easily going to graveyard, the spell should be powerful enough even in the early game to bring what's most needed here : mana. We need to out some cards, and I choose to replace Moment's peace with Songs.

Third change : mana acceleration and drawing. Krosan Tusker is nice but heavy : 3 mana to cycle is a lot. Planar Chaos brings us a Green Time Shifted Sindbad : the common Fa'adiyah Seer. It can only start to work at turn 3 (cast at turn 2), such as Krosan Tusker, but it leaves you with 3 mana free for doing whatever you want. It can be used to dredge or simply draw, and eventually fill your graveyard, which is not bad in this deck.

Fourth change : the side. Moment's peace is so good and usefull we can't afford to trash it. Dark Heart of the wood and Nourish can be left away, since we need mana and the deck should go faster with its new mana acceleration. By the way, Seal of Primordium is strictly better in this deck than Naturalize : it's an enchantment you can cast "in case of", leaving you with spare mana later, and as an enchantment, you can bring it back with Rofello's gift.

// Lands
11 Forest
10 Swamp

// Creatures
4 Sakura-Tribe Elder
4 Fa’adiyah Seer
4 Stinkweed Imp
4 Golgari Brownscale
4 Crypt Rats
4 Spore Frog
1 Battlefield Scrounger
1 Eternal Witness
1 Uktabi Drake
4 Tortured Existence
3 Sylvan Library
1 Demonic Tutor
4 Songs of the damned

//Sideboard:
4 Moment's Peace
3 Rofellos's Gift
4 Crumble
4 Seal of primordium

Please feel free to comment this list :)