Ok, he followed me for like a mile, flicks his lights on, I pull over. Mind you I've done nothing wrong... he comes up and asks for license and insurance. I hand my license and start rummaging my glove box for my registration. He asks me what I'm looking for... I say my insurance card. Find it and hand it to him. I'm nervous because I've only been pulled over a couple times ever... he asks if there's anything illegal in the truck. I say no. He asks if I know why he pulled me over. I say no. He asks again if I have anything illegal. I say not that I know of. He says "what might be in there" I answer with I don't know of anything. He asks me to step out. Asks if I have weapons on me. I tell of my pocket knife. He takes it out and says ill get it back when he's done. He starts patting down my other pockets and asks whats in them. Phone, gum and keys... he says I can sit down in my truck. Goes to his car for several minutes. Comes back amd gives my license, insurance, and knife back and asks me to set em on the seat. I do. Then he hands me the ticket and says "you don't have to go to court if you don't want to... any questions?" I say no and he walks away.
Yeah he went fishing and you handed him the bait.
75% of the time if a guy says things like "there shouldn't be" or "not that I know of" or "I don't know of anything" they end up finding something. It's the liars way of setting up the "it's not mine" defense.
You looked nervous - understandably - because most people are. He asked you the same question repeatedly and you gave him three different answers. He was looking for anything but the same answer every time. To an experienced officer that is indicating someone is looking for the truth.
Next time simply say "no" every time he asks about the presence of contraband. Or "no sir" if that vernacular is customary in your area.
Also, keep your insurance card and registration more handy.
Question - what time of day was this? Traffic conditions? Urban or rural?