This looks like a black walnut tree, but the "nuts" are not those of a black walnut.
Hive in a big tree trunk. (I think it was a Coast Live Oak.)
High up & mostly hidden, so not great pics. Maybe Downy?
Saw two individuals here, plus a few more around the park.
Light lemon scent.
Biggest one I've seen. At edge of lake.
Two individuals here.
Two observed/pictured (across lake from each other).
Large colony (near picnic area - note the peanut).
I cannot identify the species of this tree. Every year around the middle of summer, it bears large, spherical buds that drop from the tree all over our driveway. The outside is soft and there is a large, hard nut inside.
This looks like a native but was growing in someone's yard. Note the fruiting bodies in the second picture.
Most likely a cynipid wasp.