Halloween has it's origins in England (Pagan origins?) not the USA but they have turned it into the monster it is & that now affects the UK. Folk are free to celebrate/mark whatever they wish but no need to bring it to your door & expect you to pay for the privelege
I also object to being asked Penny for the Guy outside our local, Kwik save, Cellarfield, co op or whatever they're called this month. Depending on what head i've got on that day i'll either think "little scamps" & give 'em a £1, give 'em a penny!!! show them my driving licence as proof of my name & ask them for a penny or point to the pile of old clothes they pass off as a Guy & tell them to make a proper one. 
Halloween is indeed a pagan festival, but it did not originate in England as there was no England until 937 under King Athelstan, and was only realistically unified after the Norman conquest, when the governance was centralised and the Doomsday Book compiled late in the 11th century.
The customs associated with Halloween have been derived from the beliefs of the druids, the Celtic priests of ancient Gaul and Britain.
Many of the ancient peoples in Western Europe would celebrate the end of the harvest season with a holiday in late autumn. The most important of these holidays to later influence Halloween customs was the Samhain, which was celebrated by the Celts of Western and Central Europe in the first millennium BC.
The Samhain, which occurred on October 31, also marked the beginning of a new year in the ancient Celtic calendar.
According to Celtic pagan religion, the druids believed that witches, demons, and spirits roamed the earth on the eve of November 1, which is known as All Saints' Day - a holy day in the Roman Catholic and Anglican churches. The holiday honours Christian saints and was established by the Catholic Church in the 9th century.
The ancient druids used to light bonfires to ward off evil spirits. In order to protect themselves from the devilish tricks of the evil spirits, the druids would appease the spirits by offering them treats.
The druids would also disguise themselves in costumes so the spirits would think that the druids belonged to their own company. This is where the custom of wearing costumes on Halloween originated.
'Trick or Treat' as we know it today is very much an American custom.
Almost all pre-1940 uses of the term "trick-or-treat" are from the western United States and Canada. Trick-or-treating spread from the western United States eastward, stalled by sugar rationing that began in April 1942 during World War II and did not end until June 1947.
Early national attention to trick-or-treating was given in October 1947 issues of the children's magazines Jack and Jill and Children's Activities, and by Halloween episodes of the network radio programs The Baby Snooks Show in 1946 and The Jack Benny Show and The Adventures of Ozzie and Harriet in 1948.
The custom had become firmly established in popular culture by 1952, when Walt Disney portrayed it in the cartoon Trick or Treat, Ozzie and Harriet were besieged by trick-or-treaters on an episode of their television show, and UNICEF first conducted a national campaign for children to raise funds for the charity while trick-or-treating.
As for "Penny for the guy". I wonder what reaction I'd get if I gave them a penny, picked up the 'Guy' and said "That's a bargain, cheers !!"