I never thought of swallowing them either - but they made wonderful caltrops when combined with Pla-Dough or Silly Putty.
I honestly believe that a lot of kids are frankly over-protected and sheltered. Our playgrounds had blacktop surfaces - if you fell, you skinned your knee, and the school nurse slapped a band-aid on it, maybe some peroxide if it was particularly bad. Jungle gyms looked like some half-finished construction project, or mad plumbing. Heck, at my elementary school, there was also a six to ten foot length of concrete pipe - the kind they use to run water under streets - for us to climb on.