@fleamarketfabulous,
This is a type of decorated net lace. These appear to be curtains. Net lace curtains like this were popular in the 19th century. They continued into the 20th century, but by then were more likely to be made completely by machine, instead of hand decoration on machine-made net, which is what yours are.
https://web.archive.org/web/20140712015837/http://www.laceguild.org/craft/decoratednets.html#
These are machine made net, with a pattern formed of muslin (thin, finely woven cotton) outlined with chain-stitch embroidery. Then the muslin was cut away from the background areas, leaving the net background. The chain-stitch embroidery was probably made with a tambour hook, which was much faster than using a needle. The Lace Guild article does not identify exactly where this type of lace was made or what it was called.
The best-known lace that used muslin on net was Carrickmacross Lace, which was made near the town of Carrickmacross in Ireland. However, in Carrickmacross lace the outlining is a couched heavy thread, not chain stitch, so your curtains are a different kind of lace, though related.
https://en.wikipedia.org/wiki/Carrickmacross_lace
It looks as though someone may have cut some of the medallions out of the lace to use for something else. In the late 19th and early 20th centuries, lace medallions like this were sometimes appliqued onto white summer dresses, so they may already have been upcycled when they went out of fashion as curtains.
