This diminutive plant arising from gravelly or sandy ground is Nevada Onion (Allium nevadense), a member of the Onion Family (Alliaceae).
Each flower has six petals, and the flowers are arranged in a ball. About five inches underground is an onion-like bulb.
Appearing as bright spots of color in wet areas, Seep monkeyflower (Mimulus guttatus) is the most common monkeyflower in the area, hence another common name: common monkeyflower. It's listed in the Plants Database as a member of the Figwort/Snapdragon Family (Scrophulariaceae), but I understand this is under some contention.
It has five petals, with little red spots on the lower petals. The leaves are broad, oval, and serrated. They are opposite and often fuse around the stem.
We saw numerous white thistles in late May next to the road, and they turned out to be New Mexico thistle (Cirsium neomexicanum), also called desert thistle. 
The flowers can be white or purple and are up to 3 inches across. The bracts are tipped with spines.
The leaves are spiny.
We are lucky to have numerous penstemon species in this area. This one, with its large fleshy leaves and big, pink flowers is Palmer's Penstemon (Penstemon palmeri). It's also called scented penstemon, balloon flower or pink snap dragon.
The upper two petals provide shade for the flower structures below, including the large staminode with its pompom of projecting hairs. The lower three petals curve downwards, with a lighter pink surrounding the dark pink middle.
A small plant with a ball of flowers emerging from the stem looks different from many of the families we've looked at. This is Fragrant White Sand Verbena (Abronia elliptica), and it's in Four O'clock Family (Nyctaginaceae).
The plant grows in sandy soils, and the flowers will open even more.
Plains pricklypear (Opuntia polyacantha) is especially striking when it's flowering. This jointed cactus typically has numerous flower buds that bloom in May-June.
The flowers are usually yellow and pink or red (see below), spreading about 3 inches across. The green part in the middle is a globular stigma, and it is surrounded by yellow stamens. The petals are nearly translucent.
Many of the cactus flowers we looked at had insects on them. This species grows up to about 10,000 feet in this area and is able to withstand freezing temperatures.
The spines are in clusters of 5 to 11, and the cactus is considered to be clump-forming.
While walking across sagebrush country, marshmallow-sized white flowers caught my attention. They rise up about a foot off the ground and upon closer inspection are clearly members of the Sunflower Family (Asteraceae). A little research shows they are Douglas' Dustymaiden (Chaenactis douglasii), also called dusty maiden, pincushion flower, chaenactis, and hoary chaenactis.
There are several different varieties that vary with elevation, but the ones with sagebrush have full, beautiful flowers. The 1/2 inch wide flower heads have many tubular disk flowers and reproductive parts emerging from them, making the flower look somewhat like a pin cushion.
