I use buy the dorans blade and first because its a great starting item, it can also help you with first blood. Then on to the berzerkers graves because, they give you enchanted movement 2 (which is really all you need) and 25% added attack bonus, great in the beginning. Then onto malady, this gives you 25+ ability power, making your mushrooms stronger, quite strong in the beginning, also slowing your foes down, but this also gives you 50% attack speed, getting you closer to maced attack speed. After malady i get wits end, this item gives you 40% plus 30 magic resist but also its passive gives you extra damage which is nice. After getting wits end i stack 2 phantom dancers, for one reason, 60 percent critical, which will rape, you max out on atk speed which is good and your movement speed will be fairly high, enough to easily escape from a gank. Lastly i get bloodrazor because you would have a lack of attack damage, this will give you that extra boost to do tons of high criticals

I always max toxic shot first so i can do heavy damage early in-game, and blind shot 2nd because it deals a good amount of damage, plus it blinds your foe, making him miss his basic attacks for a short amount of time, move quick at level 17 because, its helpful, but only for advancing to your line faster or running, which isnt just as important as hellious damage, i max the mushrooms out last because your gonna have too.

Pros:
HELLAAAAA DAMAGE once you finish this build
Cute
Fast is you get boots
Avid Farmer
Wonderful AS/AD Champion
Cons:
Very squshy
Low HP throughout game
Can't plant too many mushrooms with the amount of mana it has
Screwed if he gets ganked

You wanna farm your shrooms pretty much EVERYWHERE. Like really, every bush there is, corners and most importantly, plant them at all the places where you can get buff's, the more the better, because with mushrooms all over the map, you and your entire team get a much more extended view of the map, know when groups of foes are coming