Mystery plant, wild flower maybe?

[user1471542018]

We got an offshoot of this from an area of scrap land last year, and stuck it in a pot, this year it’s about 5 foot tall and looks like a thistle with no prickles. It has little blue flowers and the bees seem to love it. Any ideas what it might be?

looks like chicory

I think you are right, thanks very much!

It's not chicory, because chicory has the flowers on shortish stems, so they are all very tight up the main stem in a single column. Your flowers are on longer stems so they stand out from the main stem. It looks like a blue lettuce, Lactuca sp. (there are several species with blue flowers).