Aged mystery eggs produce better prizes? Cornish eggs produce FV cash? Golden eggs produce Hens?

I was reading TheFaceGamer and from what it says mystery eggs that sit on your farm produce nicer things.  One person told me they left a golden egg on their farm for four days and it produced a hen.  The best part is you can put the hen in your chicken coop, awesome!

Although, aren't all the chickens considered hens since they lay eggs?  Also, aren't the Cornish chickens really considered to be Cornish hens?

Another rumor is that the Cornish eggs will produce fv cash if left to age so I am going to find out how true this is.  Today I received my first Cornish egg and it is sitting on my farm now, aging.  For a little extra nitch I am leaving all my eggs on my farm and am going to hatch each one in four days, the next in five and so-on.  Could this be why people leave those mystery gifts sitting on their farms?

Have you done this, or are you doing it?  Leave your comments, what did you hatch in your eggs by waiting four days?  Did it work and have you tried this so-called easter egg yet?  Comments are welcome :)

Update - Hoarding gives you better chickens:

If you read my comments, I figured out in a few days that saving my eggs on my farm for more than two days gave me better chickens.  If I opened an egg that day usually I got the same gifts, gold chicken, school house, gold gnome, etc...

What really sucked was when after hatching a golden egg the same day my prize was a farm helper, ack!  So if you want a rhode island, Cornish and/or scots grey chicken, I suggest hoarding those eggs for at least three days.

Is there really Farmville cash?  I am unsure and what I need to do is be patient and try to save an egg for a longer amount of time.  Mystery gifts do seem to give neater gifts if you wait.  For example after a few days I got another chinchilla and different color pinwheels.  The same goes for these as well though, I need to wait more than four days to see if I get better gifts than that.