Where do they all come from?

I started weeding the first garden plot today! Its the biggest one too. It was much easier and more satisfying than weeding the bits of weed that sprouted up in the rocky walkway. The big weeds were in clumps, so when I pulled  part of it, it made it easier to pull the rest as they were all attached to one another. So far, I've pulled out half of the overgrown mint and all of the green onion I planted months ago. My next goal will be to remove the rest of the mint and begin on the other two plots.
 I encountered one spider (but it was so bad) and a TON of pill bugs! They were scattered throughout the soil as I was pulling out the mint. I wasn't as freaked out as before as I've dealt with roly polies many a times, and I started a new strategy: pull the weeds quickly and stuff them inside the trash bag before I see some bugs or insects. I feel bad for the critters because I'm tearing up their home, but hopefully they'll enjoy the new garden more!
EDIT: So I just found out that pill bugs are actually crustaceans. Who would have known? Here's a link to more fun facts about them.

Tuck and Roll from "A Bug's Life"