Sedge field is both Sugahara and Sugawara, the Japanese family names. Sedgefield is a family name (and a place-name) in English too, so that might help you with this one!
This is a very old surname, said to have originated with Nara period scholar Hanishi-no-sukune (土師宿禰) who changed his name to Sugawara-no-furuhito (菅原古人). Historically, the name has been associated with scholars and writers, including prominent Heian period statesman, scholar, and poet Sugawara-no-michizane (菅原道真) and noblewoman, writer, and poet Sugawara-no-takasue-no-musume (菅原孝標女), also known more simply as Lady Sarashina in the English speaking world.
The only reading you haven't learned for this name is the irregular わら reading for 原, so here's a mnemonic to help you:
Sugawara-san went to war a (わら) long time ago, but these days he enjoys a quiet life tending to his sedge fields.
Sugahara's a cool surname, isn't it?
Oh, Sugawara-san, do you have a cold?
At Sugawara Shoe Store, I bought a pair of stylish leather shoes.