Moses baskets - we keep buying and never using. My babies were velcro babies so didn’t want to sleep anywhere but on me.
Snot removal sucker - gross and never got the courage to stick it up a baby’s nose!
Newborn baby clothes. They always ended up being too big, so used 0-3 months.
Various slings and wrap-arounds. Some were so complicated and confusing that I didn't bother trying to figure it out! I also worried too much about carrying them, and used sturdy baby carriers instead.
Colostrum harvesting - only heard about this in my latest pregnancy, and still think it is a myth! Couldn’t even get a drop. Bought all the kit for it hoping that it would help the tide the baby over while my milk came in.