I googled 'Thistle of Scotland' and found the following:

Features - The Rebels - Ceilidh Song Book - 'THE THISTLE O' SCOTLANDO, the Thistle o' scotland was famous of auld, Wi' its toorie sae snod and its bristles sae bauld; Tis the Badge o' my Country, it's aye dear tae me, ...
www.scotsindependent.org/songbook/thistle_scotland.htm

But then I couldn't get the link to open!

If anybody can get to this page, we'd have the words to a fine song.

BTW, I think the word aye (yes) should be ay (forever).