This list contains foods that are moderate to high in beta carotene:
bell pepper of any color, red being the highest in carotenids
dandelion greens (raw)
fava beans in the pod (raw)
grape leaves (raw)
lettuce (dark varieties, not iceburg which is nutritionally empty)
pumpkin and squash, and seeds (dried)
snap beans (raw)
seaweeds and microalgaes
Astaxanthin is another carotenid found in shrimp and krill and red seaweeds, that the crabs also use.
Tannin is also a color booster. Dried oak or sycamore leaves, or raisins help provide this substance.