[warbler73]

Marjorie Rice. Housewife.

https://www.quantamagazine.org/marjorie-rices-secret-pentago...

Her discoveries first mentioned in a 1988 magazine when she was 65.

[wikfwikf]

The discovery of these pentomino tilings is an interesting achievement and evidence of an exceptional mind, but it's very far from a major advance in mathematics.