Wolf's milk slime mold

Hi Alison.. I believe yours are galls and not slime molds. The reasons are 1. Wolf's milk is never found on alive leaves (almost always damp timber) 2. The color looks wrong to me 3. (most importantly) yours are actually deforming the leaves around them which a slime mold would never do.
If you know the species of the leaves then it might help a lot with working out what the builder of the galls is. A rough guess would be wasps or midges. Good luck with it. :)

Wow, that's amazing! :-)

Galls - http://fineartamerica.com/featured/oak-l...