It looks a lot like Alstroemeria roots. They do need to be still attached to a portion of crown to grow, though.

Oops looks like thats the end of that then! Mind you I need to create space for my long awaited summerhouse that I will be welcoming into my garden the end of May....can't wait.

Tug I found it almost impossible to dig out what is a weed alstromeria in my garden. It just keeps coming. as soon as I see any greenery coming up from it I pull it out.
Amsterdam pop them in a pot and see if anything comes up. It is worth a try rather than losing the plant. There is still a chance the original plant has sent out runners which will appear in time. Good luck.