This poem talks about poverty meals. Beans on toast are compared to nasty haggis,/another meal derived from dregs my Celtic mother's kin/prepared in times long past-the boiled protuberant/stomach of a sheep stuffed with heart-and liver-studded porridge,/then oven-boiled for hours till it swelled with seasoned, gaseous pressure/and threatened to explode. Actually, this description of what (in spite of, is it Dunc's perennial claims?, is supposed to be food fit for the Gods), sounds like a truly awful meal, is one of the best parts of the poem. N goes on to muse that with prayers and toasts/ to Robbie Burns-the haggis on a bed of spud was a conquest of sorts.
if we had thought to serve our meager, almost-payday meal/ on our one and only silver-plated tray, we might have seen/ our lives in some kind of new relief, and bent our heads/to our beans and toast with a kind of pride,
I THINK she is trying to tie the service of the beans on a silver tray to the idea that haggis is uplifted by its connection to Robert Burns. The idea being that the beans didn't have anything similar, therefore, they were more onerous and life was more depressing. And the logical extension is, I guess that you can enjoy poverty and starvation more if you are Irish and you have romantic or heroic "stuff" to think about. Or maybe that's just the way it seems if you are a kid. Or nostalgic. Or that maybe her mother should have just tried harder to disguise their poverty. Or all the above.