It seems a bit odd saying "Halloween Lore" as Halloween is all lore really, here's some stories and traditions associated with the 31st of October
The current name comes from "All Hallows Eve" but like other celebrations such as Christmas and Easter, the roots of the celebration go back to Pagan times to the holiday of "Samhain" (pronounced Sah-ween) which signified the end of summer.
The Druids of Ancient Britain, celebrated Samhain on October the 31st or thereabouts, the date falls between the Autumn Equinox (22nd September) and the Winter Solstice. It marked the end of the harvest and the start of the "darker half" of the year. The eve of Samhain, October the 31st was the night that the Lord of Death judged the souls of the departed.
For the Celts in particular, Samhain was the biggest and most significant holiday of year. They believed that at this time the ghosts of the dead were able to mingle with the living. The souls of those who had died during the previous year would travel to the other world.
As might be expected from ancient Pagan festivals, there was much drinking of very rough brews and chucking away of food and other goodies in a melodramatic manner to please and appease the gods.
There are rumours of human sacrifices, though no-one has ever found any evidence. The purpose of the Samhain festival was to ensure that the following year would produce good crops and give people a chance to communicate with departed ancestors and assure prosperity. Some claim that wisdom from ancestors could be learnt at such times - I'm more sceptical as they kept on drinking those brews not learning their lesson and I reckon didn't feel too clever come November the 1st.
In 834 AD a full two centuries after Britain had embraced Christianity, the Pope ordered that the continuing Pagan rituals that still continued against attempts to ban them should be Christianised. So spring fertility rites were absorbed into Easter, Winter Solstice / Yule celebrations were absorbed into Christmas and Samhain became All Saints Day - a "Hallow" was another word for a saint and the eve or evening before made it All Hallows Eve, eventually becoming Halloween.