LulaSews

It may seem like it should be a pepper, since that would go better with the flavour of a tomato (and the mass produced modern ones are admittedly more pepper shaped), but it is and has always been a strawberry. Here are some antique emery strawberries, which are much more strawberry shaped, and some of them have seeds.

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(Home Needlework Magazine, 1899)

And it's for cleaning needles, not sharpening them. I can't imagine how jamming a blunt needle point around in a bunch of loose grit could possibly sharpen it in any significant way, and all the historical sources I've seen only talk about cleaning.

"Every sewer's work basket or work box should contain an emery bag, as shown in Fig. 2, through which to push a needle when it becomes rough, squeaks, or sticks in the material. An emery bag is usually shaped like a strawberry and consists of a rough denim bag filled with emery powder, which is a very hard material used for polishing metals. Such a bag may be purchased for 5 or 10 cents in any store that sells sewing materials. Needles often become rusted from the perspiration of the hands or from being left in damp places. The beginner may use a small emery bag to remove rust; or, a small piece of emery paper may be used instead."

-Woman's Institute Reference Library, 1916.

"Use an emery whenever your needle does not slip through the cloth easily."

-The Improvement of Educational Administration in Massachusetts, 1916.

"An emery bag is inexpensive and is useful to keep needles polished and smooth. If the hands perspire and it is difficult to push the needle through the cloth, running the needle through the emery will relieve the condition."

-Boys' and Girls' Clothing Club, 1915.

"It was very hot to sit and sew. The needle would get sticky in spite of all the little emery strawberry could give it, and Beth's fingers had never felt so clumsy and uncomfortable."

-The Unitarian Register, 1908.

"She polished her needles to nothing, pushing them in and out of the emery strawberry, but they always squeaked."

-Rebecca of Sunnybrook Farm, 1910.

This patent from 1873 mentions an emery slab for sharpening pins, which is quite different from a cushion, and which sounds like it actually would work for sharpening.

"C is a slab of emery or other sharp and fine grit, for sharpening needles or pins"

Then later down the page it also says

"E is an emery cushion, secured in the body of the holder A, and is used for polishing needles and keeping them smooth."

So. Strawberry for cleaning. Not pepper for sharpening.