Solved Some kind of thorn tree but which?

I have this volunteer tree in the back yard which has thorns. I like it's shape and plan on keeping it after it's dead neighbour is removed.

The berries right now are gree vut they turn black in the fall. I ate one last year and didn't die so I'm wondering if it is suitable for making jellies. Anyone know what this is please?

 

The leaves look a bit like buckthorn.

 

Agree with mazambo...
Rhamnus cathartica, the buckthorn, common buckthorn or purging buckthorn,

Quote wiki.....classified as an invasive plant in several US states and in Ontario, Canada.

frangula cathartica leaves - Google Search

Never try berries before knowing what you are eating!

Quote wiki.....Toxicity
The seeds and leaves are mildly poisonous for people and animals, but are readily eaten by birds, which disperse the seeds in their droppings.[9][10] The toxins cause stomach cramps and laxative effects that may function in seed dispersal. The chemical compounds responsible for this laxative effect are anthraquinone[11] and emodin. The species name cathartica and the common name purging buckthorn refer to this effect.

In 1994, R. cathartica was implicated in the outbreak of an idiopathic neurological disease in horses,[clarification needed] although no causative agent was officially identified. In trials where rodents were fed the leaves and stems of R. cathartica, glycogen metabolism became abnormal and glycogen deposits formed in the cytoplasm of liver cells. Abnormalities in glycogen metabolism lead to diabetes in humans.

 

I was just reading up on buckthorn but nowhere does it say it is native to my area. It is about 25 feet tall. So it certainly likes it here.

Edit: was reading a site that only talks about the UK... silly me!

 

Thank you for this information. It's now a sure thing I won't be making jelly from these berries!