(11:32) The people rose up all that day and all the night and all of the next day and gathered the quails. The ones who gathered the least collected ten heaps. And they were spread around the outside of the camp.

We can explain that since the quail were spread around the outside of the camp, the ones who were situated at the outer extremes of the camp collected the most quail because they could collect almost unlimited amounts. But those who were situated far away, that is, those in the middle of the camp, had a long way to go there and back to the place of the quails, and therefore they were only able to collect ten heaps.

And the reason why they collected only ten heaps is because the gemora in Pesachim says that a person can walk ten parsas in a day. Therefore, since the posuk says that they collected for a day and a night and a day, they were able to walk thirty parsas in that time. And since the size of the camp was three parsas, those who lived in the middle of the camp had to walk three parsas there and back to collect the quails. Thus, they were able to make the trip only ten times and hence the posuk says that the ones who collected the least, that is, those in the middle of the camp, collected ten heaps.