There was an Elizabeth Lovelock buried in Beenham on 5th August 1827 aged 70 (so born in about 1757) - see the Berkshire Burial Index on FindMyPast. This may, or may not, have been "your" Elizabeth, wife of James Lovelock. Check the original of the entry for any more clues. If so, then it doesn't fit with the Elizabeth Hissey of Longworth as the ages don't match (although sometimes ages were approximate). It may have been another Elizabeth Lovelock though. No obvious burial for James Lovelock in Beenham though - your wikitree source has him as dying in 1822 in Crondall, Hampshire, which seems unlikely though it is of course possible. Wikitree again is simply a place where people put their family trees, which are only as good as the research which has gone into them, so always check the sources and never rely on someone else's research unless you can trust it.
The William Hissey who died in Beenham in 1790 was a pauper, according to the Berkshire Burial Index - there might be more information on him amongst parish chest records for the parish (eg records of the overseers of the poor) if these records survive for Beenham. Try the Berkshire record office to see what records of the Beenham parish they hold.
