PUFF
PUFFBALL
PUFFBALLS
PUFFBIRD
PUFFBIRDS
PUFFED
PUFFER
PUFFERIES
PUFFERS
PUFFERY
PUFFIER
PUFFIEST
PUFFILY
PUFFIN
PUFFINESS
PUFFINESSES
PUFFING
PUFFINGLY
PUFFINGS
PUFFINS
PUFFS
PUFFTALOONAS
PUFFY
PUFTALOON
PUFTALOONIES
PUFTALOONS

26 words start with PUF.