These are strawberry tree fruit.
I don't know why they don't sell them in stores, because they are delicious and they look really magical. They grow a few blocks from here and I saw them about a week ago and didn't know what they were or if they were edible. After some research (thank you Internet) I discovered that they're not poisonous. The Wikipedia article says that they taste bad, but it's not true. They taste similar to plums, and the only thing people may not like about them is that they're spiky, and therefore feel grainy when they're chewed, but personally, I like that. YUM!