The Vega is the most amazing tire option for picking stuff up. Used to swear that you could get every tiny piece of shit off a floor by making two laps with a clean tire.
The Hoosier treaded or slick tire, even in D20A, doesn't pick up nearly as much crap, like orders of magnitude less.
Biggest rock was something like a giant pea
Worst was the constant glass shards. Like 20 a ride here in Miami. Constantly removing them. Now I get one every fourth or fifth ride. Once had one that was a spike an inch long and driven right into the tire... Slime worked. Pretty unreal.