It took me a while to figure out what this tree was - while it looks very similar to Blackthorn, it's actually a Cherry Plum, which is often confused for a Blackthorn because the flowers look identical.

In any case, cool plant facts! Blackthorns are typically bushes (this was a tree), and bloom later than Cherry Plums, which usually start mid-February without the leaves (which makes sense, as this was taken Feb 25).