I am sure the question everybody is asking when watching How I Met Your Mother is “Who is the mother?” Well I have been doing some research, and this is what I have found.
What We Know So Far
The Yellow Umbrella symbolises the mother
Ted has met her roommate (and has seen her foot)
Ted met her at a Wedding – (not sure who’s wedding, but one of them)
She does Economics 305 as Ted was in her lecture
It’s definitely not Stella
The mother’s name is Tracy
In Season 1, Episode 9, Belly Fully of Turkey, a burlesque entertainment artist approaches Ted and says what he did was sweet and introduces her as Amber and later adds “Actually, I’m Tracy”. At the end of the episode, Ted says “And that kids is the true story of how i met your mother.”
The kids believed him, and Ted then says “I’m just kidding.” If Tracy wasn’t the mothers name, the kids wouldn’t believe Ted when he said, “that’s how I met your mother” (referring to Tracy).
That girl Ted bumps into in Episode “No Tomorrow”
In the episode around 13min 49seconds, Ted bumps into a girl on St Patricks day. Ted does mention that the mother was in that bar and that they never met, but bumping into to each other is not meeting someone. The image on the left is the girl Ted bumps into, and the image on the right is the girl refers to as “the mother being there.” However, looking at these two images, the jeans look a little different. So are these two people the same?
The Love Solution match that Ted never meets
Remember when Ted goes to Love Solutions to find his soul mate, and a match wasn’t found? Months later, they call Ted and tell him that they found him a match. Ted organises a date with her to meet her, but he never goes to it because he is still in love with Robin. This unknown person may also be the mother.
It’s Robin’s Sister
How else do you your kids call someone Aunt? If Ted marries Robin’s sister, then Ted’s kids will call Robin Aunt Robin. We have met Robin’s younger sister once in Season 2 Episode 12 “First Time in New York”. But does Robin have an older sister?
Myth #5 (Most probable)
Barney’s (Half?) Sister
One other possibility is that the mother is Barney’s half sister. Since Barney doesn’t know who his dad is yet, he will later find him, who will have a daughter. And as Dash said in the comments, when Barney’s Brother, James Stinson adopted a baby, this was how Barney became uncle Barney. So Barney is Uncle to his brother James’s kid, and will become Uncle again when his sister has a child with Ted.
Update: In the episode Legendaddy, Barney meets his real father and it is revealed that he has a daughter called Karly who is in collage, and that his father lives near by. It has been mentioned that the mother was in an economics class that Ted mistakenly lectured at. Also, because we didn’t meet her when Barney was at there house, it can mean that she lives elsewhere – I.e Cindie’s house. As per meeting the mother at the wedding, this will be Barney’s wedding, possibly with Nora (in which Barney’s sister is introduced into the show) and that’s how Ted and the future mother meets)
Zoey’s Step Daugter
As Sarah points out in the comments, the mother may be Zoey’s step daughter. Ted mentions in one of the episodes that Zoey is not the mother and the relationship “did not end well”. In the show, Zoey’s step daughter is perceived as a little girl, but going on “The Captains” age, she could be around Ted’s age. Since we know Ted meets his wife at a wedding, the wedding could be between Zoey and The Captain, thus Ted being introduced to Zoey’s Step Daughter. The reason Ted could be at the wedding is because Ted and the captain remain best friends.
So that’s my thoughts on who is the mother in HIMYM. Who do you think is the mother? Do you even think the kids have met their mother? It’s open to you for discussion, I would love to hear what you think.