yes you can. after all thats what happens in the wild.
clear a patch of soil of weeds etc and rake til a good crumbly soil. then cover the seed about 1-2cm 1/2" deep. keep weed free and watered.

or start them off in good seed compost on a window sill and then transplant when big enough to plant out.

Yes, it should be OK to sow the seed in this manner in spring. How big is your garden and do you want more than one plant - they are large? Unless you want lots then you might be better sowing in a pot and transplanting.
In the early 19C there was a lady known as Miss Wilmott. She used to visit gardens and sprinkle a few Eryngium giganteum seeds around the flower beds. The plants germinated and grew after she had left! To commemorate this tale there is an Eryngium giganteum 'Miss Wilmott's Ghost'.

I am also interested in this variety of Eryngium,Bulba..
could you please tell me how large ,approx..height and width ?

I've tried this several times and not had any plants to show for it. I suspect slugs and snails have seen off the seedlings.

Well, I suppose about two and a half foot high and wide, Bloomer. We have grown it but never really measured it!

Thanks Bulba..that's near enough.. and thanks for doing it in measurements I don't have to convert ! :o)