Maybe that's why they traditionally had berries depicted on slot machines.
Or else they use things like gold nuggets or diamonds, which have the same intermittent reward mechanism.
There is even a whole subset of mushrooms called the 55-mile-per-hour-mushrooms, so called because they're especially easy to identify while driving at highway speeds. Here is an old post referencing this: http://mpb.ou.edu/ben/ben416.html
I've also dumpster dived a little bit (decent amount of crossover between foragers and dumpster divers), grocery stores toss out tons of food that's still perfectly good.
This is completely foreign to me. Do these people drive by bushes and quickly scan for berries and shrooms to pluck? In the actual real world?