You know what they say: behind every successful man is a wise, loving mother with an inexhaustible fount of clichéd sayings. (We might not be remembering that quite right.)
Mrs. Gump's main character trait, we see, is a deep love for her son, leg braces, IQ of 75, and all. She dedicates herself to giving him a normal life and convincing him that he's just as good as everyone else, which makes her a pretty darn good mom in our eyes. Take what she says when Forrest gets upset about being different: "If God wanted everybody to be the same," she says, "he'd have given us all braces on our legs."
Notice how she makes having braces the standard? She's so dedicated to her boy that she's willing to rewrite basic biological facts—most people don't have braces on their legs—in order to make him feel good.
She's also willing to perform some rather unpleasant biological acts in order to ensure that he gets every chance at a normal life. When the principal of the Greenbow public school tells her that Forrest can't attend, she says, "He might be a bit on the slow side, but my boy Forrest will get the same opportunities as everyone else" and then proceeds to ensure that he does by having sex with the principal.
Seems like a radical act just to get her kid into a school that probably hasn't seen an updated textbook in 20 years, don't you agree? Maybe. But, attending public school also puts Forrest into a situation where he can get a football scholarship and go to college—which is more than most people with average IQs can say.
Forrest is definitely a momma's boy, and one of the ways we see this is in his favorite phrase, "My momma always said ..."
It's easy to make fun of Mrs. Gump's folksy sayings, such as: "Life is like a box of chocolates. You never know what you're going to get"; "Stupid is as stupid does"; and "You can tell a lot about a person by his shoes." But let's give her some credit: Mrs. Gump knows her son. He's got an IQ of 75; he's not going to respond to philosophical musings about fate and destiny and character. Those concrete metaphors and easy-to-remember phrases stick with Forrest, giving him comfort and direction everywhere from a school bus to a jungle in Vietnam.
Right before Mrs. Gump dies, she gives Forrest one last piece of advice. "Death is just a part of life," she says. "Something we're all destined to do." Trite? Yes. True? Also yes. After she dies, Forrest may be a momma's boy without a momma, but he'll always have her words to guide him.