The book Wildflowers of the Pacific Northwest by Mark Turner & Phyllis Gustafson ($27.95) organizes flowers by color and family. The plant descriptions are understandable by ordinary people with technical terms graphically described on the inside of the cover.
The book Wayside Wildflowers of the Pacific Northwest by Dee Strickler ($19.95) has a useful visual guide for finding flowers. The plant descriptions are understandable and the pictures are large. This book does not describe as many flowers as Turner which can help when finding a common flower but may not help with less common flowers.
helps you identify Oregon and Washington wildflowers using information about the flower, location and time of year. There is information on California, Idaho, Montana, British Columbia and Wyoming wildflowers, too.
by Mark Turner (see first book above) advertises his flower photographs. However, it contains most of the information in the book along with additional pictures. It has an advanced search algorithm that could be a real help except that it contains bugs and often does not find the right flowers. Pointers to additional web sites are included with each plant description.