Wylla

 Since we know very little about her, other than what she was Jon's wetnurse and the person who Eddard said was Jon's mother, I might have developed a few headcanons for Wylla here:

• She was a handmaid to Lady Ashara Dayne, and the daughter of servants of the Daynes of Starfall.
• She followed Lady Ashara to King's Landing when Elia wed Rhaegar.
• Still, Wylla stayed when her Lady left back to Starfall because she had married another servant, a cook named Petyr.
• Petyr died shortly after though, and Ser Arthur Dayne sought Wylla for becoming the handmaid of Lady Lyanna Stark, who had started a relationship with Prince Rhaegar.
• Even if she only accepted because it was Ser Arthur who asked her, she came to love Lady Lyanna like a sister.
• Wylla also happened to be pregnant as more or less the same time as Lyanna, but she lost her child.
• When Lord Eddard came with the plan of disguising Jon/Aegon as his bastard, she was the one to offer herself to be the mother, should he need to mention anyone.
• She also nursed Jon until they arrived to Starfall to bring back the sword "Dawn". She was welcomed back there by her former mistress, Lady Ashara.
• She wasn't there when Ashara commited suicide. If she had been, she would have done everything to stop it.
• Wylla has stayed at the service of the Daynes so far, being the wetnurse to their heir. Edric.
• She also married again, to another servant of the Daynes, and has two sons and three daughters.
• (more to be added)