Wildflowers: Tiny flowered plant

I found this plant in a drying-up ditch in northeast Idaho near Henry's Fork of the Snake River. Its four-petaled white flower is tiny - about 3/8" across.The bud is pink/purple, and the trunk and branching structure is extremely delicate.
Can someone put me on the path to identification, please.

 

Gayophytum sp.

 

As usual, Andrey, you're spot on.
I think I've narrowed it down to Zigzag Groundsmoke (Gayophytum heterozygum)
Thanks,
Rip

 

Not listed for Idaho:
http://bonap.net/NAPA/TaxonMaps/Genus/County/Gayophytum

Probably, G. ramosissimum/decipiens/diffusum

 

I stand corrected, Andrey.
Even though the specimens I found were very close to the Montana border, I think the description of Gayophytum ramosissimum better fits. I think the common name is Branchy Groundsmoke.
Again, thanks for your help.
Rip