Dreven is a man who looks after the bush farming patch outside of the Champions' Guild south of Varrock. He will not look after Poison ivy bushes though, because they cannot become diseased.
Players can use him as one of the five gardeners in the A Fairy Tale Part I quest. Dreven is part of G.A.G., the Group of Advanced Gardeners.
Dreven also sells basic farming tools, which can be accessed by talking to him and asking Can you sell me something? It is not an actual shop and it has no set stock; each item has to be bought individually through the dialogue.