I live in the UK and my local farm shop sells turkey eggs; they are slightly longer in shape than chicken’s eggs, but about the same width/diameter, the surface texture is white mottled with light brown and they have a smooth glossy feel.
The shell is much harder than a chicken’s egg and the membrane inside the shell is very tough indeed (it’s quite tricky to crack them without breaking the yolk - a major disadvantage in terms of commercial desirability I think).
The flavour isn’t anything remarkable at all, but this is probably mostly because the turkeys and chickens are fed pretty much the same diet.
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Cecil’s column can be found on-line at this link:
Why can’t you buy turkey eggs in stores? (06-Mar-1998)
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Oops, I meant to, really I did
No worries. We’ll forgive you just this once. BTW, are you the same M. Mangetout that I’ve seen mentioned in the Guinness Book of World Records? If so, I would think that you would eat the shell of the turkey egg.
Are the turkey eggs much more expensive than the chicken eggs?
No, I’m not the French guy famous for eating glass, planes and an entire birch tree (but I do like a variety of foods)
I’ve only bought the turkey eggs once out of curiosity and I seem to remember that they cost maybe about half as much again as hen’s eggs (although they were larger anyway).
I probably won’t be bothering again because of the difficulty cracking them (my favourite way to enjoy eggs is fried, and sandwiched in nice soft white bread, but the yolk has to be whole and liquid so that it runs all down my shirt)
Rumour has it that the original M Mangetout, after a successful career of dining on such things as light bulbs, bicycles and wooden chairs, choked to death on a strawberry.
although that might just be a myth
In this thread:
http://www.straightdope.com/columns/991008.html
Cecil affirms that female turkeys are capable of reproduction without :o sexual intercourse.
Given the description Mangetout gave, I suspect turkey eggs are very hard to candle.
Finding a little embryo turkey on my plate at breakfast time would put me off turkey eggs for good. 
Cause & effect?