When we kept chickens, ducks and geese (also peacocks) They roamed free, they were not kept in enclosures, this meant they were scratching around all day and eating seeds and all manner of things from the ground in our field and the local fields and this makes the eggs that deep yellow colour and give them a good flavour. I would add we supplemented their feed with chicken pellets and also at one time all the left overs from the local school dinners.
If you buy from a farmer, you need to know if his birds are kept in enclosures, if they are he just feeds them chicken feed and this means the flavour of the eggs is not as good.
Also, depending on how many chickens he is keeping he could have them in a barn and not allow them out at all and you have no way of knowing the eggs are only one week old.