Soft fruit recommendations

I have a Tayberry which is Thornless grows in habit like a blackberry by send out runner. canes from the main plant, it really wants a support structure as it does better if you grow it up or through something else. It will grow new plants where the tips hit the ground like a blackberry does.

It’s prolific and produces long fruit which don’t quite go black in colour. It tastes sweeter and has more depth of flavour than either the raspberry or blackberry parent plants. Will grow in semi shade and quite likes heavy ground. I’ve never seen it struggle with any kind of pest or disease though birds and squirrels will pinch the fruit.

When picking the colour changes from raspberry red to a really dark maroon almost black colour, it should slide off the stem like a raspberry when ripe but will snap off like a blackberry if a little under. You can hack back older canes it will come again every year if you want to keep it neat and tidy, or push a tip into the ground if you want to produce another plant.

If what you’ve seen is darker and blacker than this it might be a mulberry.

I used to spend a fair amount of time in a mulberry tree as a kid, so I don't think it's that unless they actually differ here from what I grew up with. A definite possibility given some of my experiences.