Weeds in my yard. At the slightest touch, the dried seed pods "explode", flinging their seeds in every direction. Not sure what plant they are (bittercress? jewelweed? something else?), let me know if you can identify it. UPDATE: the consensus seems to be that this is bittercress.
These were captured with a Casio EX-FH20 I borrowed, at 420- and 1000 fps.