Some widely creeping species such as hay-scented fern can be propagated by cutting a portion of the plant itself with a sharp spade and then skimming under it and removing it like a piece of carpet.
The roots go only an inch or two deep, and the rhizomes are so dense that they hold the soil together while you replant.
You will have better overall success dividing ferns in early spring before the fiddleheads (the developing fronds) unfurl. The fronds are more likely to flop if the plant is dug when the fronds are completely open, even though the plant itself may survive.
Make these beautiful FIY fern table numbers for your wedding or event: