Hi, this is a tree growing in a relative's yard. They were wondering what it was, and if the nuts growing on it are edible? Someone mentioned they were a type of chestnut (inside the fleshy pod), but I'm not sure. Thanks

It looks to me like black walnut (Juglans nigra).

Reminds me of Black Walnut too! Scroll down the database page for a lot of images for comparison: Black Walnut (Juglans nigra)

It cannot be a chestnut. It is a walnut, for sure, most likely a black walnut. If the nut inside the green husk has deep ridges, at least as deep as ,then it is. More smooth points to other types.

If you dig into the husk, be prepared to stain your hands black.

I see the tree is about to damage the fence as it grows in to it.

on walnut and also about the fence

Walnut.

These trees get very large, they are a hardwood tree with a long life span. They are squirrel magnets. They drop large amounts of nasty smelling, staining nuts. These trees will ruin the fence, they are planted way to close to it for long term. If they were mine, I'd remove them now before they got any larger. If there are power lines near by sometimes the utility company will remove trees for free, they do here. You may catch a lucky break.
It is also difficult to get other things to grow in the area where they are.

Thanks for the info - and my relative w/ the tree just mentioned about the fence. By the way, they were also wondering if there is any (eco-friendly) way of preventing it from producing the walnuts? Short of cutting down the tree?

nothing that I am aware of. I would love to hear about it if there is.

It's definitely black walnut, I have one behind my yard. There is no way that I'm aware of either to prevent walnuts, that's just what it does If I could cut it down I'd do it in a minute!