At the very beginning of the play, Tom (as the narrator) describes to the audience that it is a "memory play", hence it has:
"...dimly lighted, it is sentimental, it is not realistic."
These features prove to the audience and reader that dreams often have to do with illusions and the lack of reality, which is a central theme in "The Glass Menagerie".
TOM: "I give you truth in the pleasant disguise of illusion."
Also, what is very evident while analyzing the characters is how their dreams often distort the reality around them. They use their dreams as tools to soothe the frustrations of their lives in the present.
The character Amanda, Tom's mother, constantly brings up her past, for it is something that comforts her from the harsh realities she faces in the present. The word "dreamer" in regards to the character of Amanda can signify different things.
In relation to her past and how:
"One Sunday afternoon in Blue Mountain, your mother received- seventeen!- gentleman callers."
The word "dreamer" in this instance implied that she regularly "dreams" about her past in order to escape the reality of her financial situation and her frustration with Laura. Therefore, in this context, Amanda is a "dreamer".
On the other hand, in regards to Amanda wanting Laura to get married, is not quite a dream, but more of an "obsession", as Tom calls it. Since Laura is "crippled", realistically it would be difficult to find her a suitor and this is why Amanda "obsesses" over this. The last thing Amanda wants her daughter's destiny to be is:
"Ã¢ÂÂ¦eating the crumbs of humanity."
Through this, it is clear to the reader and audience that Amanda's "dreams" and "obsessions" blind her from reality: that maybe that kind of life might be...