Before you start, think about what you want to search.
Annual Report of the Bureau of American Ethnology [Secretary of the Smithsonian Institution/ Main Reference (E51. U55 50+ volumes).] They are available online, but if you are here, I suggest looking at them in person. Each volume begins with the annual report (usually quite short), and then it moves to “Accompanying Papers”, which includes artwork. These papers are generally more than 100 pages each and cover a wide range of topics for North, Central, and South America - including shell art, Navajo weavers, prehistoric textile fabrics, pictographs, ancient Pueblo pottery, form and ornament in ceramic art, ancient art of Colombia, sand painting, picture-writing, Omaha furniture, and katcinas.
Handbook of North American Indians (Main Reference E77. H25/ multiple volumes) Includes volumes for the Northwest Coast, Plains, Contemporary Society - and any of these might provide the information you want. Each has its own index - so, for example, in Volume 7 (Northwest Coast), check the Index for art - you find entries for abstract design, human motif, painting, postcontact adaptations, and so on.