The Medlar is also known as Mespilus germanica. These trees produce large white flowers in late spring and small rounded fruits which can be picked in. These fruits were very popular in medieval times but now adays not as widely grown. This fruit is usually harvested in autumn but the are generally still hard and bitter at this point, they need to be storage for several weeks so they can ripen and turn into dark brown, soft and sweet. At this point they can either be eaten or uses for fragrant amber jelly or used in sweet desserts. The medlar fruit is very rare to buy so best to grow your own. https://www.rhs.org.uk/fruit/medlars/grow-your-own