Outside of the lane the Teemo was laning in that he would have time and leisure to place shrooms at every corner of that lane, otherwise outside of it all Teemo players due to efficiency reasons will always place shrooms either in the middle of a small brush, maybe 2 in large brushes like at the top and bot lane, in the middle of the lane to delay pushing, and in the middle of a choke point if there's no brushes there.
This isn't to say all and every Teemo will follow this exact pattern of shroom placements, but you should have a pretty good idea about where some of those shrooms are even without visually confirming their location and you can avoid them via skidding past them by sticking to walls, staying behind minion waves and have them trigger most of the shrooms in the middle of the lane, or something along that line.
Obviously, if you have to brute force it, there's the control wards and things like Banshee's Veil, too (outside of red trinket). Or you can just try and tank it out.
Concerning if you're one laning against Teemo, buy a control ward and place it in the brush in the lane that's closer to your turret, and renew it if it gets destroyed. That way most of the lane placement would be moot and Teemo can't also ambush you in the conventional way for the most part without you over-extend.