Wild teasel (Dipsacus fullonum) is very distinctive and should be readily identifiable. The smaller but similar small teasel would be the only outside chance of mistaking it for.
It is sometimes hard to know when a teasel is in flower and when it is in seed, the flowers are very small and give just hint of blue/purple in the head as they appear from what look like tiny compartments. The seeds then develop in those same compartments. The wild teasel is a tall, prickly plant that can grow to six feet or even more. When I say prickly I mean very prickly, the stems, the leaves and the flower heads are all very prickly! The plants stand firm well after flowering and can still be in place the following spring and re a popular food source for finches, especially goldfinches in winter. Teasels readily grow anywhere where the is dry, bare soil and can overrun and colonise waste places and even rough grassland.
There is a cultivated form called Fuller's Teasel and the dried flower heads of those are sometimes used in flower arranging. This variant was also used in the textile industry many years ago for combing out wool and cotton prior to spinning but this is not, of course, the case now.