Marjorie Rice was a housewife and mathematician interested in art who discovered new pentagon tilings of the plane.
She was inspired to work on tilings after reading in Martin Gardener's column that the list of pentagonal tilings was "complete", contradicted a short time later by another reader submitting a single new pentagonal tiling.
She took that as a challenge and then, over two or three years, discovered over a 100 new pentagonal tilings. She created her own notation which helped her categorize the tilings into several types. Her work was verified by another female mathematician, Doris Schattschneider.
Here's a five minute video by a girl giving an introduction to tilings and Rice's contributions. The video's very well done and inspired me to post this here.
Here's a recent magazine article talking about how her discoveries fit alongside other mathematical discoveries. It references journal articles and her own essays discussing her work, as well as including many quotations by her daughter talking about her mother's process.
Of the 15 tiling types known today, she discovered 4 of them. There's a 2017 proof that claims that these are the only 15 tiling pattern types which use a single convex pentagon repeating, although it does not appear that this proof has appeared in any journal.