As promised several days ago, I went outside again with my stacked lens setup.
This time I've got my technique worked out a little better, and was able to use a tripod and a more realistic ISO setting (200 instead of 1600).
The top two are the tiny stamens of two different geranium flowers. The whole whorl (collection of stamens) measures about 2 to 2.5mm in diameter (1/10 inch). The final shot is to give some context to what you are seeing.
Thanks to Theen for the pointer on what the various bits of a flower are called.