So I have experimented with all the species of flower that I find around me since I live a mile from good chuck habitat. read: Chucks are still there as of now......Godzilla was not too picky an eater, but favored dandelions (greens and flowers) to everything else. Also eaten were rose petals, Toad flax, Bok choy flowers and leaves, cilantro, tomatillo flowers, fruits and leaves.
so here's the rough list I've compiled
PS my Chucks always left the poppies alone, but I had a Desert Igg that ate them from time to time.
1)Five-needle Fetid Marigold-Dyssodia pentachaeta
small yellow flower, favored by herbivorous lizards
2)Chichweed- Pectis papposa
another yellow flower, not as popular as marigold
3)Desert Marigold- Baileya multiradiata
Large Yellow flower, grows right on the hills near basking sights
4)Desert Dandelion- Malachothrix glabrata
resembles a large dandelion (mixed success with these; some liked them some didn't)
5)Snakehead- Malachothrix coulteri
basically the same as desert dandelion, with similar results
6)Mojave Desert Star -Monoptilon bellioides
white daisy looking flower. favored by all.
7)Desert Chicory- Rafinesquia neomexicana
variable color most are white though (individuals prefference, the Iggs really liked them though)
8)Esteve's Pincushion- Chaenactis stevioides
White flower not really a pincushion in the spiny sense.
9)Coulter's Lupine- Lupinus sparsiflorus
Purplish "Bluebonnet" Tortoises liked this more than the Chucks, although they were eaten from time to time
10)Desert Bell- Phacelia campanularia
Blue flower also growing right on the hillsides. watched wild chucks take this flower
11)Scalloped Phacelia- Phacelia integrifolia
lavender flower, loved by all Chucks i've kept
12)Mojave Aster- Machaeranthera tortifolia
light purple to blue, watched wild chucks take these as well.
13)Indian Blanket- Gallardia pulchella
reddish flower with yellow trim. Eaten sparsely, the collared Lizards I had liked them more.
14)Globe mallow- Sphaeralcea ssp
orange flowers, loved by all herbivorous lizards I've kept
15)Desert Willow- Chilopsis linearis
lavender to dark purple blossoms. a staple flower in my Chucks diet.
There are many other flowers that I've tried, but i don't know what their names are. My identification book is the Audobon Society Deserts field guide. It was printed in its 7th edition in 1992. With all the splitting that goes on expect some of these species to be changed. Go with the genus when searching these flowers out. Anyway, I hope that helps.
good luck,
-Phil