The plants you are seeing have had the nectar tapped. They are on the berry bushes with nectar. I don't know if it's true with all fruit bearing, but I assume it is, that once the flower is fertilized it stops producing nectar. Fruit blooms are short lived but even with unfertilized flowers the plant produces a very small amount of nectar a day. A single bee needs up to forty to fill it's nectar gut and those flowers slowly regenerate the supply. Watch bees in a field of clover or other plant that doesn't fruit and you'll see them hover smelling for nectar and move on, and move on and keep checking out flowers until they find one that hasn't been tapped yet before landing. These pit stops can be very short on cloudy days as the plants don't produce much nectar without sun and enough moisture in the soil.

Blackberry is next and a few of the others with white pollen include wild strawberry and elderberry.

 

http://www.mybeeline.co/en/p/pollen-identification-color-guide

 

Jewel weed pollen is almost pure white, maybe that's it

 

Jewel weed is a late summer bloom (at least for me).

 

I am in your backyard near Deer Park and have noticed the same thing. I kind of thought it might be from all of the Canola fields. This is my first year and I am amazed at the variety of colors they bring in.

Do you know the rough dates of our flows and dearth's in this area?

 

Oh right on, I didn’t know anyone from BS lived that close. So it seems like usually late July or early August though mid September. Then there seems to be a tiny flow in late September/early October. But it varies and I honestly haven’t payed enough attention to that kind of thing.

 

Hey guys, my girls are bringing in a lot of white pollen ...

Cichorium intybus L. .
Bees like it a lot.
Cultivated or weedy.

 

Raspberry is grayish…my guess is Mock Orange….I’m in Chelan, 1,500’ and it’s blooming hard here.

https://en.m.wikipedia.org/wiki/Philadelphus_lewisii

 

We do have a bit of mock orange blooming here. I bet that might be it.

 

In my neighborhood (Seattle area), raspberry bloom occurred in early to mid-May. Around that time, the whitish pollen my bees brought in was mostly from hawthorns. However, I do not know the major plants in your area that bloom along with raspberries. It could be raspberry (light tan), thimbleberry (light tan), Pacific blackberry (light grayish), wild roses (light tan), rhododendron (white), or snowberry (light tan), and possibly more…

 

https://www.metrobeekeepers.net/wp-content/uploads/2014/04/PollenColorChart-Sheet1.pdf

 

Matches the Jewel Weed color.