i got a store bought raspberry plant and planted it out in mid march (3 months ago) but its not showing any signs of life apart from this odd thing growing out at the base. it looks like a weed but ive never grown much so dont know if its supposed to be like that???!!!

also shouldnt it have developed some growth and leaves by now? its still just the same bare branch it was when i got it

Looks a bit like maize or something?
Maybe some bird seed has fallen into the pot and germinated?

The raspberry should be showing signs of life now.
Try digging the thing out and seeing if there are any shoots coming from the rootstock.
Sometimes, this kind of disturbance can set the thing growing again.