Free things turn up in a handful of places. They work differently, which is why checking all of them by hand takes time.
Community giveaway groups
Freegle is a network of local groups where people post things they want to give away, such as furniture, appliances, kids’ stuff and garden items. You reply to the poster and agree a time to collect. It works best when you check often, because good items go fast.
Classifieds
Gumtree has a Freebies section in its For Sale category. Anyone can post there, so quality ranges from nearly new to scrap. Listings usually say what the item is and where it is.
Online freebies and samples
Brands and retailers give away samples, trials and promotional items. These are not things you collect from a house. You follow the offer and sign up with the brand. Read the terms, since some need an email address or a purchase elsewhere.
Doing it in one place
FreeStufzy reads from several of these sources and shows them in one searchable list. Each listing links back to the original post, so you always deal with the source directly.