please be restrained in peeking them because it will expose the location of the nest to the predators of robin's eggs (or babies) such as crows,bluejay, hawks. those birds are smart. they stay on top of a tree surveying your neighborhood. when they see you are peeking something in the bushes, they know there is likely a bird nest and they will check then destroy the eggs/ babies.
Robins are very urbanized birds. they eat earth worms and other insects. they 啄your菜 is out of curiosity or to check if there is a worm or an insect. they are not vegetarians.no worry. when they appear on your lawn, it means spring is here (for northern states) . they have beautiful songs. Here is a book about them: The American Robin: A Backyard Institution, by Len Eiserer http://books.google.com/books?id=jhVr0O1U2sgC&pg=PP4&lpg=PP4&dq