Name That Tree: Yellow and Green Baseball Sized Fruit Edition

[This is another tree identification post, where I try to identify an unusual plant that I come across in my neighborhood.]

Yesterday, while running on the Capital Crescent Trail I noticed the following fruit along the side of the path:

It's hard to tell scale from that picture, so you'll have to trust me that it's a baseball sized object. Which was strange, because that's a really substantial fruit to not be able to identify. There didn't even look to be trees nearby that would be big enough to produce such a fruit. Still, there were enough fruit lying around that I was pretty sure it didn't just fall out of someone's backpack:

We continued to run along the trail, and just when I was starting think that perhaps someone just dumped of a box of fruit they bought at Whole Food's, we saw yet another bunch of the mystery fruit. So, what was it?

I turned to Google Images and initially had no luck finding it. Searching by the characteristics didn't turn anything up. Then, it occured to me: we don't have an awful lot of fruit trees here in DC, what with our winter and all. So search for Washington DC Fruit Trees, and sure enough, on the first page I saw:

There was the mystery fruit! According to the linked page, it's a Hedge Apple. Officially, the plant is named Osage Orange, it doesn't appear to be found heavily in the DC area.

As for uses, there are a number:

• At least one page says the fruit is edible, though most pages say it's not. My guess is that few people want to go through the trouble of extracting the edible seeds from the fruit.
• A common use of the fruit appears to be as a pesticide. However, the jury is out as to whether this actually works.
• The tree does have a novel history, as it was apparently used in the Great Plains Shelterbelt, a massive project started in 1934 to deal with soil erosion.
• Some claim the wood is ideal for making bows from.
• The most common use of the fruit appears to be that of projectile among kids. Depending on where they are grown, and when they are thrown, they either make a most excellent Splat! or are frozen rock solid and are near deadly.

So there you have it, mystery solved.