I have seen many Osmia females bringing this bright orange pollen back to their nests.
It is very conspicuous....
These bees do tend to specialize on composite flowers for pollen (aka Asteraceae family) so I'm narrowing it down...
Arrowleaf balsamroot?? But that's all the way in the foothills... I'm seeing this pollen brought back to boxes the middle of town.
Dandelion?? Hmmm... let's hope not. Bad for business ;)
Any ideas?