saw an old 2017 post blaming england for davie not getting to see the flowers again before his death. besides that being just a little silly...
...i guarantee you that davie never thought about those flowers again.
america is the only one who brought them to his funeral. (there's no other blue flowers. davie's family didn't find them to have specific sentimental value, evidently.)
america repeatedly brought them up throughout his lifetime, and davie was never interested.
i think that was the point! it was a beautiful/fleeting moment of a human's childhood that was unnaturally elongated through america's weird semi-immortal existence... and it started to rot!
america's perception of time is so strange that he searched for those flowers in the field for over a decade before he finally gave up. at that point, why would davie remember the face of a child he met for a few hours, once, many years ago (against all logic that the child should have aged by now?)
this was america's first experience with/true acknowledgement of his immortality and inhumanity. it's SUPPOSED to be lonely and isolated and unnervingly quiet. we get the feeling through various colony!america comics that while america adored england, he left america alone a lot...
so eventually america started seeking companionship from his citizens... other kids "his age." they look like him, don't they? (<- creature who is unaware of his nature as a human facsimile)
america is easily distracted, and he's also a lonesome, skittish kid who prefers the wilderness.
as it's been said before... it's not impossible this is america's first real interaction with a human. it's not impossible he's simply failed to notice up until now that humans come and go pretty quickly. evidently, england didn't explain to america that getting emotionally invested in humans is a very bad idea (unlike the op's claim, this IS something england can be faulted for!) the comic is america running around in confusion and pain for 60 years, give or take.
imo, the davie comic is just a representation of what would become one of my favorite theme's with america's character: a lonely desire to be human beyond his capability. he's so enamored with humans, he's an immortal being who is jealous of the mortal lifestyle. he wants those passionate, short-lived human connections so badly (like 'father and son,' 'husband and wife' etc)! but it's just too painful. it's like watching a movie on 100x speed, you're just bitter you can't experience it how you should.
there's a big wall between america and the human family there, and i'm pretty sure it's named "davie."