Also known as Sulfur flower and Buckwheat, Eriogonum umbellatum is one of my favorite native plants of Wyoming. It consists of a ground cover of small ovate leaves 4 inches high and topped with flower stems 8-10 inches tall. In my gardens it has grown to cover a 24 inch circular patch. In Wyoming we have four varieties.*
In the photos you can see the most obvious distinction between varieties is the flower color. Eriogonum umbellatum var. umbellatum and aureum have bright yellow flowers. I think the one in the photo is variety aureum.
Eriogonum umbellatum var. dichrocephalum and majus have beautiful creamy flowers. The one in my area has a white cast on the leaf undersides. The blooms turn a beautiful rosy color as they mature and dry.
I have collected seed from this plant and plan to use it in my sandy yard in full sun.
*Dorn, R.D. 2001. Vascular Plants of Wyoming
Wyoming Life 
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HI! I visited your blog and tried to comment, but the commenting seemed to be disabled. It looks like you are building an interesting file of native plants. So many of our natives have anecdotal evidence of medicinal uses. It’s a very interesting topic.
I especially wanted to comment on your unknown white wildflower which looks similar to wild onion. It looks like Zigadenus. The photo is out of focus, but I’m pretty sure. Zigadenus, or Death Camus, is quite poisonous!! Please be careful! There is probably a herbarium at Sheridan College. You may want to take your samples in there for positive ID.