Worms are tricky because the audience has never actually heard one — earthworms are basically silent in real life. What you're really making is the audience's idea of a worm: wet, slow, slightly disgusting movement underground. Get the moisture content of the sound right and a body-horror shot lands; leave it dry and the same shot feels like a sock dragging across carpet.
Across these 23 recordings you'll find soft soil burrowing, slick squelch movement, faint slither and a few muffled underground scratches that work great pitched down for larger creatures. Game audio teams use them for parasites and crawlers, nature shorts use them under macro shots, and horror editors layer them beneath body-transformation cuts. Take whichever fits, free MP3, no signup wall.