Cop says I knocked over a cone, I know I didn't. Help!

walnut, california. i was on valley going east and i made a left turn onto grand avenue. about 30 seconds later a cop pulls to the left side of me and tells me to pull over. the officer told me he saw "me" go westbound on valley and as i was making a right onto grand avenue i knocked a cone over (on the ticket it says distrupting a cone pattern). clearly in my mind i knew i was on valley heading eastbound. my home is also west of this valley and grand intersection so there was no way i could have gone westbound. but i didn't argue, got my ticket and rushed to school to take my midterm in genetics. my court date on the ticket is around april 23/24. i don't know exactly how to prepare my case and i need some help. i also took pictures of the intersection and all of the cones were on valley going westbound.

It's cops like that that gets under my skin

Tell the judge that that particular cone was protruding out of allignment by several inches from the others and would not have gotten hit if they had properly located it. For 25 $ I will testify as a witness for you.

To start off, where were you coming from? If you were coming from a friends/relatives then you can use them as a witness. Meaning you would have to be driving east and not west to be coming from their residence. Anyway, just a tip.