I know this because I've stepped on my fair share. For some reason kids just don't leave Lego men together.
I also know this because it is one of the items I found in Shiloh's diaper last night. She'd been pretty cranky all day, and I knew she needed to poop. Finally, results! Also found in said diaper -- part of a ladybug, a glob of paper (source unknown) and a small piece something else that I could not identify.
Update on the hives:
I had hives for well over a week, but about the 3rd or 4th day we figured out I have an allergy to cashews. Explains why I never really felt the need to even try them during the first 32 years of my life!