Why is it that Buddhist monks are strongly associated with beggars?

It seems to be a strong affinity in media for monks to be beggars. There doesn't seem to be anything in Buddhism that effectively correlates to being poor, or even using begging for livelihood. The Noble Eightfold Path even has occupations in one of the folds, and doesn't recommend too much of a constrain to the point of driving people poor. Specifically, I would put the book Buddha Boy by Kathe Koja on display, where a Buddhist boy moving into a rather bad neighborhood is picked on at school for his actions, one of which is begging for food during his lunch period. In this example, "Buddha Boy" begs for food, however, that doesn't seem like anything I've seen in Buddhist culture. Is this a common misconception, or am I misinformed?