Here are my favorite wildflower ID sites:
Lady Bird Johnson Wildflower Database: http://www.wildflower.org/plants/
My Wildflowers: http://www.mywildflowers.com/index.asp
Discover Life: http://www.discoverlife.org/mp/20q?guide=Wildflowers
As you try to identify your plants, take note of the number of petals and the types of leaves - they are very helpful in distinguishing between two very similar flowers. In addition, notice whether the leaves are on the stem or base, and whether they are opposite each other on the stem or not.