Plants for a tricky spot...

I have a raised bed/compost pile that has a black walnut   sapling growing out of it.
It's not in a good place for a mature tree and black walnuts are hard to shell anyway.

The bed is located inbetween two houses, with a six foot fence immediately to the north of it, and a twenty foot pear tree beyond that, so the sunlight is very poor.

I think the jugalon is preventing other plants from colonizing the bed  but it might just be the chickens doing.

I'm thinking of coppicing  the sapling and planting asparagus, but I'm looking for other ideas.

Hi William,

Currants, gooseberries and sour (or acid) cherries (bush cherries) will do well in the shade.

Cheers Scott

I think volunteers are great, but if they pop up in a place that will significantly affect your other plantings, I'd consider them more of a weed (plant in the wrong place) and remove or move it.  Especially if it's an allelopathic plant like black walnut.  

If the fence and the pear are to the north, and you're in the northern hemisphere, is the shade coming from the two houses?

Hmm,  I know nothing of currents or gooseberries.
Do they take a lot of pruning?
Sour cherries would be amazing, but how big do they get?
I'm not scared of roots,  but I don't want a wide tree

The houses are about 10 feet apart.
The bed is against one house and the fence, on the other side of the bed is a 2 foot wide path and then the second house.
The pear is about 3 feet from the fence, and it has another black walnut sapling growing two feet in front of it!
I planted the pear, rescued from the end of the year sale,   knowing it was a poor location, but not have a better choice at the time.
It had thrived,  but the location means it mostly fruits up high,  presumably because that where it gets sun.
I have been unable to bring myself to prune it in any serious way, but that is another topic.

The bed is inconveniently placed, but very rich,having been a much peed upon compost pile for a couple of years.
I have considered tearing it down and moving the soil,  but that seems like waste of good ecology.
I'm amazed the sapling grew there  but that is what gives me hope for anything else.

I have considered planting comfrey, and coppicing the saplings for poles.

Here are some photos to make things clearer.

Possible plants:
6ft blackberry/raspberry
6ft juneberry (regent/prince edward)
6ft goumi
10ft Artic Kiwi shade loving vine
8ft elderberry

Maybe these sun loving plants
3ft-5ft suncurrant/gooseberry/jostaberry plant, they taste tart and sweet think sour cherry.
Jujube