Health freaks online call them Tiger Nuts, Flemish farmers and gardeners curse them as (the meadow ruining) Knolcyperus.
But every Valencian grandmother on the other hand knows them as Chufas, the basic ingredient for Horchata, a traditional refreshing summer drink.
I love them as a snack - soaked in water they are like crunchy sweet almonds -
or as flour for my home made bio-cookies.
Chufas in spanish 'fruto seco' shops: 6 Eur/kilo.
Don't tell me that Super Food is expensive.