Looks like an iris seed pod. If it didn't taste nice it should be the warning to your daughter not to eat things that she can't identify.

Totally agree.As many things can be posionous.

Iris foetidissima, I would have said. Not too bad for a first try at making herself ill, but that's probably all it will do at worst. 'Harmful if eaten' is the description my Poisonous Plants book says, but mild effects, tummy ache etc. The taste is usually enough to put people off!

As an addition to the above - the book to which I refer is most useful in many places, home, schools etc. It's called Poisonous Plants, by Elizabeth A. Dauncey, after much work by Guys and St Thomas Hospitals, and published by Kew. For those who don't know it/haven't a copy, it's really clear and concise. Costs £15.

Its a good example of how important it is to involve children in the garden and the countryside at an early age and teach them its very important only to eat things you have shown them are OK. Even then you have to be careful eg some red berries are fine, some just taste nasty and some are best not touched at all. Stick to blackberries while they are very young as there's no mistaking them.
And nothing at all that's growing in the flower bed...

As has been said, a bad taste is often found with potentially harmful berries.

Just one thought about Worthy1's book recommendation.

It is based around the Horticultural Trades Association list of potentially harmful plants. GC's don't like drawing attention to such plants so the highest grade 'Class A' has only one plant in it, and that plant no GC would ever sell.

That means you need to read Liz's book on the basis that Class B is the highest risk (but that risk is still small).

I have to disagree with Steragram. Accidental poisoning sometimes results from poisonous plants growing in amongst brambles. A small number of people don't spot that not all the berries in the hedge are blackberries.

I've heard of at least one blackberry and deadly nightshade pie.

Thank you everyone for your replies. Don't worry we have had the "poisonous berries/safety" conversation and my daughter is old enough to know better. But think it has scared her enough to cease experimenting.

Glad to hear no lasting damage, Dangerous, and hopefully a lesson learned.

Blackberries - when I said show the children, that would include pointing out the "Loads of tiny berries stuck together" rather than one big one. Admittedly dewberries sometimes have only one or two but they are nothing like nightshade are they?