Classic granny square (US terms). Worsted yarn, 5 mm hook. Finished size about 12 cm.
Round 1: Make a magic ring. Ch 3 (counts as first dc), 2 dc into ring, *ch 2, 3 dc into ring* rep from * 2 more times, ch 2, join with sl st to top of ch-3. (12 dc)
Round 2: Sl st into next ch-2 sp. Ch 3, (2 dc, ch 2, 3 dc) in same sp. *Ch 1, (3 dc, ch 2, 3 dc) in next ch-2 sp* rep from * 2 more times, ch 1, join. (24 dc)
Round 3: Sl st into next ch-2 corner. Ch 3, (2 dc, ch 2, 3 dc) in same sp. *Ch 1, 3 dc in next ch-1 sp, ch 1, (3 dc, ch 2, 3 dc) in next corner* rep from * 2 more times, ch 1, 3 dc in last ch-1 sp, ch 1, join. (36 dc)
Round 4: Sl st into next ch-2 corner. Ch 3, (2 dc, ch 2, 3 dc) in same sp. *(Ch 1, 3 dc in next ch-1 sp) twice, ch 1, (3 dc, ch 2, 3 dc) in next corner* rep from * 2 more times, (ch 1, 3 dc in next ch-1 sp) twice, ch 1, join. (48 dc)
Fasten off and weave in ends.