I could be mistaken, but it sure looks like what's known as a "puffball".
which is actually a form of fungus. In western Oregon they grow in moist
underbrushy areas, and it seems that they like growing on oak leaves or
branches for some reason. They range from a spongy, mushroom-like,
consistency to a thin woody shell. If you crush one of these balls, it
sends out a "puff" of fine dust-like stuff, which I assume to be spores.

Now that I look at your picture more closely, that sure looks like an oak
leaf to me.

I found a lot of descriptions of puffballs on the web, but not a lot of
pictures that really show what they are like, especially on the inside.
Here's one site that has a couple of good photos...

http://www.und.edu/org/ndwild/puff.html
http://host04.ipowerweb.com/~naturen...coperdon_sp.ht
ml
http://showcase.netins.net/web/grace/fun11.html


These sites were somewhat less helpful... ;-)

http://www.geocities.com/tanyaburr20...spuffball.html
http://www.ironfrog.com/libcats/map/...s/eng-puff.htm

Hope that helps. Am I close?

--Steve


Ellen wrote in
:

I've seen these from time to time in my garden. This one, if I'm not
mistaken, looked like it was *attached* to a withered ivy leaf.

I cut it open to see what was inside. Fascinating ... what is it?

TIA