The best way to describe them is as wild plums, some may have escaped from victorian gardens or later. Cooking them is best as many may be suffering from road dirt. I wish more would be used instead of being left to rot on the ground.

Someone recently asked this question but referred to them as 'Wintercracks'
we think may be a term used only in Derbyshire, but as D says they are a wild cherry plum so a veriety of Prunus, used a lot in jam and wine making

We had a question on Prunus Pissardii the other day, also edible but de-stone them before making your jam etc. I cannot recall what they are called here in the south.

They are Prunus cerasifera - as per your other post with the pic added.