I've often wondered if agriculture didn't happen almost by accident in
some cases. It seems to me that if your average hunter gatherer chucked
left over food plants out by where they were staying there is a good
chance that some would start to grow - thus saving the effort in going
elsewhere to find the plants. In this way people might have realised
that you could grow what you needed more conveniently where you
lived/stayed than having to travel to seek food.
It is interesting to note that apparently when people switched to an
agricultural lifestyle life expectancy fell significantly.